 Welcome everybody to our by engineering seminar series. It's my great pleasure to introduce my good friend, Dr. Sandeep Gopala-Krishnan. Sandeep is an assistant professor and directs the Biobehavior Research Lab in the College of Nursing at UWM. And he's an active member of McPherson I Research Institute at University of Wisconsin-Madison. Prior to joining UWM, Sandeep was a postdoc fellow in the lab of Dr. David Harder at the Cardiovascular Center Medical College of Wisconsin, where his research focused on identifying the role of auto-regulation in cerebral blood flow. For the doctoral studies at UWM, he investigated the use of near-infrared photons in the treatment of retinal injury, retinal degenerative diseases, neurodegenerative diseases under the guidance of Professor Janus Ells. And his current research involves developing and translating novel therapeutic strategies to improve wound healing. Sandeep is going to give a talk on light-based technologies in wound care. Sandeep, please. So if you can, when you have heard the introduction, you can see that the career trajectory has moved from one area of research to other to other. But the interesting as well as fascinating thing is that there are a lot of overlapping, overlapping research themes to that basic switch from one area to the other. So today what I want to discuss is basically the significance of chronic non-healing wounds and some of the interventions that are currently in place, some of the disadvantages in the context of a clinical practice and as a bioengineering student, what are some of the inputs that you can bring into the page in developing novel interventions in and around chronic non-healing wounds. So the title, as you can see, is Light-Based Technologies in Wound Care. And we will slowly go in there before even we start there. As you know, the skin is a very intact barrier and those who have taken classes in immunology knows that it's a very integral part of your innate immune system, providing you the barrier function. And you can see the stratification pattern and the reason why I'm mentioning these slides is because of the significance of different layers involved in wound formation as well as wound pathogenesis. So as you can see, it's a highly stratified layer and I don't want to go into the depth of the anatomical characterization of this organ and again, this is one of the largest organ systems in your body. So very fascinating way structures or cells are aligned in a unique fashion and there is a lot of key players in this particular cellular pool. As you can see, the carabinocytes play a significant role. The longer hand cells, which are again part of the immune cells play a significant role. So you can read through all the unique cell types that play a significant role and again blood vessels. So as you would go deeper to the skin layers, you have the blood vessels playing a significant role as well. And again, it's really interesting to know the immunological perspective of this particular structure as well because with time, the immune system has been classified as a skin-associated lymphoid tissue as well because there are a lot of autoimmune disorders that you can see on the skin surfaces similar to psoriasis, various other hypersensitivity reactions on and so forth. So the skin being the largest organ in the body obviously possesses an array of functions acting as a barrier for protection. So it basically gives you a membrane that separates your internal environment from that of the external environment. And the interesting factor is that your skin is in constant crosstalk with whatever changes that is happening in the environment. For example, the temperature in the room is changing. For example, when you are holding your pizza, whenever, for example, when you are touching the surface of the table that you are sitting, always the skin interacts with the physical, chemical as well as the microbiome phenotype of those surfaces and so on and so forth. So it's a really, really fascinating structure. So and in the physiological standpoint, it prevents dehydration and it acts as sensory thermo-libratory organ as well. And when you live in geographic locations similar to this, significance of vitamin D and its corresponding role in your immune system as well as in generating various autoimmune disorders are of huge, huge significance as well. So if you closely observe what are some of the cellular events that can happen on the surface of the skin. For example, you have the keratinocytes basically on the top of the layer. So you can have UV radiations when you wash your hand with soap or when you expose various molecules to your skin surface. It can be toxins, it can be irritants, it can be any molecules that you encounter in your day-to-day life. So whatever thing that is happening over here, you can see if it is a noxious stimuli or if it is stimuli that can generate any sort of dangerous response. You can see tons of downstream signaling pathways that are kicked in and as a result of which you end up producing mechanisms that can alter various type of cellular phenotype as well or cellular properties with time as well. So and again I don't want to go into the complexities of those downstream pathways. The overall theme here that I want to identify is that when you are exposed to a noxious or a dangerous stimuli, you end up producing a cascade of signaling pathways thereby a variety of cellular events are altered with time. So and the problem of wound healing is presumably as old as mankind itself, right? So during the evolutionary perspective you have wounds happening all over the time during that evolutionary phases of your life. And as you can see the need for surgical care of survivors of accidents or animal attacks during the early part of the evolution is part of the story of civilization, correct? As it is the story of medical care of those wounded in that other peculiarly human endeavor similar to that of warfare. So fighting each other, correct? Having various type of physical interaction should have always created sort of situations similar to that of wounds and obviously those wounds would have healed, those wounds wouldn't have healed. We don't know at this point of time, correct? So what interesting factor is that the issues revolving around wounds are there from the beginning of mankind itself. So the treatment of our wounds is an ancient art. So a lot of things that came into treating a variety of wounds constantly refined to reflect obviously improvements in the weapon technology for example. For example, if 500, 600 years ago the wounds that at that point of time was a concern was maybe a spare wound, right? A wound with a sharp object, but now it probably will be a bullet wound versus various other forms of sophistication that has emerged with the weapon technology. And war transportation, the antiseptic practices and various surgical techniques would have really, really revolutionized the way the individuals have dealt with a variety of wounds during those processes. And the reason why I mentioned that was because immense technologies that are used in the field of military science or whatever it is that you can call has been translated to various civilian emergency situations as well. So the developments in military trauma care for musculoskeletal injuries have greatly influenced civilian emergency medicine. And again that's true with various other scientific disciplines as well. So the emerging technologies that have immediate application in the field of military science down the road gets slowly translated to civilian environments. So traumatic injuries as you can see is a leading cause of mortality in almost all geographic locations. And in addition to trauma, at this point of time we are discussing in the context of trauma you have millions of surgical wounds that are created annually in the course of routine medical processes, right? So tons of surgeries happens in the clinics all the time and as a result of those surgical interventions you are basically creating wounds, right? You are basically creating a fine incision wounds in achieving a particular goal through that surgical process. Facilitating the healing of these unintended and deliberate injuries and minimizing the anesthetic. These are some of the factors that I want to mention that can translate into the clinical practice at this point of time. And there can be a variety of injuries as you can see. You can have achedial ulcers. You can have sickle cell ulcers. Or these are much more specific forms of injuries that you can see in the clinical practice. Post-operative wounds, a huge area. Correct post-operative wounds, burns. Acute wounds, acute for example when you stumble upon a sharp object the acute wounds that you are getting over there. Pressure ulcers, a huge issue in nursing homes especially in geriatric setups where you have pressure ulcers as a result of pressure forces directly interacting with your soft tissue on an extended period of time and because of the immobilization that goes hand in hand with that. Pressure ulcers, a huge clinical burden at this point of time. Chronic leg ulcers that can be from a diabetes background that can be from any vascular abnormality background all contribute to that. Venous insufficiency disorders, vascular abnormalities stimulating with time. So whatever type of wound that we are discussing over here it has huge economic burden that goes hand in hand with with the public health scenario as well. And studies around wound as well as wound healing is being there using various animal models so you can see few examples of animal models over here Drosophilia model versus the chick model versus the mouse versus the zebrafish model and again most of the information that we know at this point of time with respect to various signaling pathways involved in human wound healing is derived from studies on rodent models to be honest. And there are much more focus as well as emphasize at this point of time dealing with Drosophilia as well as the zebrafish models that you can manipulate the genotype of those organisms very fast enough they multiply faster so you can have much more a generational study with those type of organisms as well. So one of the mysteries in the field of tissue regeneration as well as repair is the heterogeneity among diverse organisms. So again there is no quote-unquote model at this point of time that exactly reflects what is happening in the human beings or unless you basically do the experimentation in the human population. So the closest model at this point of time is the swine model or the pig model which the reason is because of the nature of the tissue as well as the stratification it has that closely matches with that of the human skin. As you can see the heterogeneity is a huge issue at this point of time and some organisms perfectly regenerate in your tissues and organs there are a lot of organisms that perfectly regenerate many of the reptile organisms basically regenerate at a faster rate as well whereas others replace the damaged tissue by pathological so in the process of repairing you can have dysfunction that goes hand in hand with that you can have a perfect replacement of the tissue that is damaged or you will be replacing the tissue that is damaged with a scar tissue as well or an abnormal tissue formed as a result of that regenerative process. So in humans perfect tissue regeneration has only been described in the fetal skin so all the postnatal skin injuries will end up producing some sort of scar tissue unless it is a damage in the brain correct if it is an injury in the brain you generally do not produce scar tissue but apart from that all postnatal wounds at this point of time will create some sort of some sort of remnant tissue phenotype that goes hand in hand with that few examples are mentioned over here so for example the linear hypertrophic scar after a midline sternotomy for example if you are doing cardiac thoracic surgeries and if you are cutting your rib cage out which is technically the sternotomy you end up producing scar similar to this B is nothing but a scar from a burn injury and on the right panel you are seeing a hypertrophied scar formation which is something known as a cheloid formation as a result of pre-sternal folliculitis so these are some of the outcomes that you can expect as a result of wound healing process as well and even if you notice the wounds in your hands or in your legs or in your body at some point of time that has happened before you can see a remnant of that in your body landmarks so that is very very interesting with respect to human wound regeneration as well as healing so demographically as you can see the number of patients suffering from chronic wounds and impaired healing conditions is reaching epidemic proportions or numbers and the reason is because of the underlying physiological reasons contributed by diabetes to begin with and again the epidemic nature of diabetes and various other vascular abnormalities are obviously contributing to that which numbers that you are seeing over there so few clinically common presentations are mentioned over here you have venous leg ulcers you have the diabetic foot ulcers or DFUs obviously seen in chronic diabetes situations where you have uncontrolled diabetes for an extended period of time that progresses to various type of neuropathies and when you step on heart objects or sharp objects or warm objects or cold objects you generally don't feel that sensation because of that neuropathy so when you have diabetic disorder you don't get chronic wounds tomorrow it happens over an extended period of time as a result of uncontrolled hyperglycemia that goes hand in hand that leads to a final neuropathic situation Correct? Infections that goes hand in hand with diabetic foot ulcers very commonly seen clinical phenotype over here as a result of which you can even have foot ulcers as a result of an endocrotic or an ischemic event that is going in that vessel related anatomy pressure source another very fascinating pathology you can see in the lower panel over here arterial ulcers as a result of vascular abnormalities as well as either it can be an end result of an acrotic or an ischemic event that is going in that vessel related anatomy pressure source another very fascinating pathology you can see when you are immobilized for an extended period of time and the soft tissue pressure interactions basically drive the pathology and again all these wounds are graded in various scales you can have a grade 1, grade 2, grade 3, grade 4 which basically tells you the type of clinical trajectory of that particular clinical picture as well. Then we have chilade which again is a reflection of what you are seeing over here and it can be from a constant growth it can be as you can see because as a result of regeneration the tissue is exaggerating the response as a result of which you have extra tissue that is formed over here which is the chilade correct you have an exaggerated response to and again it depends upon your other immune factors the type of wound the layers of skin involved in that process your genotype your environment interaction so on and so on. So the wound care awareness is a really really important thing so as you can see some of the frequencies and stats over here it's a huge public health burden especially in the geriatric world it's a huge public health issue so in the US alone more than 6 million people are afflicted with chronic wounds which is replacing a major burden on the health care systems so you can see the dollar numbers over here dollar 50 billion more than many common cancers together so it is in a public health perspective even though it is less seen when you hear cancer versus a wound you generally don't feel that significant significance of those numbers with respect to a wound but it is a huge huge public health issue so 15 percentage of all diabetic patients are supposed to end up having a diabetic foot ulcer at some point of time in their life so millions are newly diagnosed every year with diabetes so obviously you can expect the number of chronic non-healing wounds with diabetic foot ulcers with time as well and especially as a result of the DFUs you end up having amputations that goes with disability that goes with your work times away from your productive years so on and so forth that again contributes as well as accelerates the economic burden associated with that so from there let's see what are some of the fascinating features associated with wound healing so wound healing after skin injury involves obviously extensive communication between different cellular constituents that we have discussed in our earlier slides right so you have stratification you have a variety of unique cells in various layers and unique properties associated with that layers as well so obviously when you are having an injury whatever may be the injury when you are having there should be immediate crosstalk between various players in that particular anatomy that should communicate with the rest of your immune system in a physiological manner thereby many many players come into that particular site to basically quench that response so different cellular constituents of the diverse compartments of the skin and obviously the extracellular matrix right the matrix that basically holds all these structures together it can be collagen it can be various other cellular matrix components so in a normal physiological condition restoration of function functional epithelial barrier is highly efficient so if you are if you are having a normal physiology and if you are having a wound you are expected to have a complete wound closure or a complete wound healing happening with X amount of time correct it depends upon the wound depth it depends upon the wound area it depends upon the other characteristics of the wound but you are expecting to have a healing event at some point of time after that particular insult correct but when you are having various type of underlying pathologies similar to that of vascular abnormalities and again I am reemphasizing the significance of diabetes or hyperglycemia over here you start screwing up everything and then discussion revolves around other things as well so the normal wound related or wound healing mechanisms are mentioned over here you have early stages world you have hemostasis you have inflammation that goes along with proliferation I think I have one more slide for it and finally you basically have the remodeling events happening correct remodeling that basically will replace whatever tissue that has been damaged with the complete functionality then only you can say that you basically remodel that correct when you are remodeling your kitchen when you are tearing down things and putting new things in that should replace the function that attributed to that particular structure that was remodeled right so similar to that you can see early events intermediate events as well as late events and finally as a result of the late event you basically end up producing the remodeling of that tissue and again this discussions are really highly variable depending upon the depth of the layers are in that are involved the area that is involved and again the superseding infections that is involved so on and so forth I am thinking about normal physiology not even in the context of any pathology that goes hand in hand with that correct so with a normal physiological background you can even expect these events to have variability depending upon the various factors that we have discussed so some of the importance so hemostasis is nothing but whenever you have a wound the capillaries are involved or the bigger blood vessels are involved so the initial response is to shut down those blood vessels so you have hemostasis which goes hand in hand with your coagulation cascade platelets various various other coagulation cascade molecules so on and so forth so think about platelet abnormalities coagulation abnormalities that can contribute to an altered hemostasis so that is a different physiological background so you basically shut down the blood supply in that particular location the reason is because if you don't shut down the environmental interaction that expose that wound to bacteria or viral material can have easy access to your bloodstream which becomes very complex with time correct you end up having septicemia so on and so forth correct you don't want that to happen so obviously the mother nature has given a fascinating mechanism by which you immediately shut down the events that is creating the leak of fluid from that site then obviously the inflammatory components in as a result of and obviously in this particular context inflammation is a useful thing correct the inflammation driven proliferation and remodeling versus in some context if you can discuss inflammation that drives pathology but in this particular case inflammation is even though driving the wound pathology it is in a good side versus in a bad side correct you can drive inflammation over here and there are tons of inflammatory players cells are there or mediators are there that can be molecules it can be various other significant events that is happening over there and as a result of these events happening the cells proliferate correct the cells start multiplying aggressively why the cells multiply to replace the damaged tissue so you basically proliferate cells start multiplying vigorously to proliferate and finally you basically remodel so you can in a context of diabetic foot ulcer or various pressure ulcers you can see all these events are one way or other compromised some events may be compromised in a higher fashion when compared to the other but these steps are all screwed up one way or other so hemostasis versus inflammation proliferation and remodeling are really really fascinating steps that drive these processes so this is in the context of a normal what happens when you're having chronic wound so when I say chronic wound these are wounds that never heal correct that's why they are chronic correct they stay for in your anatomical landmarks for an extended period of time it's really really hard to heal and the reason why they are really really hard to heal is because of the interruption in the normal wound healing process that we have seen right can obviously develop into chronic wounds as we have seen it can be a few it can be venous ulcers it can be pressure ulcers whatever we have discussed in that particular diagram a few slides back and the factors can be factors can be an issue with hemostasis factors can be an issue with inflammatory mediators playing there factors can be an issue with proliferation as well as the final remodeling so any of these events can be screwed up or compromised right that is the fascinating thing that happens with the chronic wounds and obviously you can see as we have mentioned in our earlier slide the initial events are the crosstalk between the cell populations that dictates or that basically informs the rest of your physiological system to function in a unique way correct so for example when platelets are platelets are increasingly recruited to a particular site your body should know that correct when the platelets are recruited to a particular site your body for example if you are having a large burn if you are having a larger burn when compared to the diabetic foot ulcers you need to have much more elaborate recruitment of immune cells and various other and again that depends upon a wound with an area A versus A square versus A cube whatever may be the dimension that we are discussing over there correct so it will be based upon the extensive nature of the wound you will have different players different issues with respect to that crosstalk as well so crosstalk is altered over here you start producing lack of migration or proliferation so when the cells proliferate when they start multiplying they migrate as well correct when they migrate as well and again that can be discussed in the context of migration of inflammatory cells as well from the blood vessels they extravasate to that particular site when I say extravasation they basically leave blood vessels and reaches that particular site to deal with the injuring cells correct so those type of events can happen over there as well and again you can have obviously superseded events similar to that of bacterial colonization correct bacterial colonization leading to biofilm formations and biofilm are again a huge issue with respect to chronic wounds because it is really really hard to treat infections that has biofilm phenotype associated with that as well so the overall goal is to say that we discussed the normal wound healing process now we are discussing chronic and non-healing wounds and some of the cellular players over there and as you can see the diabetes foot ulcers are again really fascinating because as a result of uncontrolled hyperglycemia for an extended period of time you end up producing neuropathy correct it can be motor neuropathy or sensory neuropathy or it can be even autonomic neuropathy correct it can you end up creating neuropathy in your peripheral sites and starts for example if you are at this point of anatomical contact with the physical environment you start producing callus the callus will be much more resistant to any sort of physical interaction so when you have subcutaneous hemorrhage over there generally don't notice that even when you step on a warm object or a cold object or a sharp object you will not be able to identify that and as a result of which you propagate that foot ulcer situation correct and on the right panel what I am trying to do here is to compare and contrast in a genotypic fashion what are some of the characteristic changes that happens in a non-healing wound phenotype so you can see and again this is a microarray microarray representation of some of the upregulated as well as downregulated genes that happens with the non healing phenotypers as a healing phenotype correct so characteristic cellular genetic events are happening in a non-healing wound which is really really a clinical burden at this point of time so what are some of the basic tenets of wound care so you basically have patient assessments you do the wound assessment by you have to diagnose what type of wound it is whether it's a DFU or a venous ulcer or any sort of pressure ulcer, posurgical wound so on and so forth you understand the etiology behind that is there a neurological component involved is there a vascular component involved is there an infection that goes hand in hand with that so on and so forth whether there are structural deformities that is happening as a result of that wound so the basic wound care wound care techniques at this point involves something known as debridement so the wound is not healing or the wound is not closing because the cells on the margin of that wound which is supposed to heal are all dead correct as a result of which you don't have a chance to merge because all those cells are dead so debridement is nothing but removing or basically scraping off those and depends upon the nature of the wound basically scraping off those dead cells so that the underlying cells which are viable or active can replace the one that is damaged so that is the whole mechanism behind debridement so you go to the clinic wound cleaning they basically clear it or debrided correct so debridement is one way so you can prepare the wound bed with various type of antiseptics antibiotics various type of solutions on and so forth off-loading or compression you reduce the pressure related to that particular site by off-loading various type of therapeutic agents can be used and again if it is really really complex you end up creating surgical interventions as well so time principles of wound bed preparations are over here which is basically dependent upon what type of tissue the type of infection as well as inflammatory response whether how moist the wound is the moisture balance in balance in nature as well as the edge characteristics of the wound so if you see I have seen a chronic wound you will be able to identify what what are the things that I am trying to explain here in that particular context so what are some of the current strategies that is in place in the context of therapy so with respect to a wound as here you have defective stem cells high level of reactive oxygen species inflammatory cytokines are really really upregulated it can be of low grade infection it can be without low grade infections proteases again proteases because of the cells that are replacing the normal cellular phenotype over there altered growth factors in that site that is why growth factors similar to that of epidermal growth factors are used for chronic non-vealing wound interventions so growth factors as well as extracellar metric degradation products lack of growth factor and again ECM senescent cells the cells that are remaining silent they are not proliferating out impaired cell functions even the cells are proliferating they can't function the role that the cell was doing before lack of vasculature as a result of which you can drive hypoxic events at that site so all these are the net result of a or in other words all these are the events that basically drives the chronic non-healing wound so you can target any of these events so you can use antioxidants you can use anti inflammatory agents anti-bacterial protease inhibitors inhibitors against growth various type of proteases to protect growth factors we don't want to have the growth factors degraded by proteases so all those type of interventions obviously growth factor by itself can be used recruit active cells in the place of senescent cells inhibition of inflammation thereby you start decreasing or quenching the reactive oxygen species of that particular site and the antigenic factors so on and so forth so there are a lot of avenues for intervention correct there are a lot of avenues for intervention understanding what are some of the cellular events that is happening underlying to this particular pathology so all those greens are always targets for so you can have a novel antioxidant molecule that can be used a one that is commonly seen in the literature at this point of time are various nanoparticles on various type of nanoparticles conjugated to various other modulators that can be used for this particular purpose as well so wound care technologies and again this is really significant in the context of a bioengineering perspective as because there are a lot of bilayered skin equivalents that is in practice at this point of time an example of that is something known as an apricraft and there are multiple other commercially available products so you can see you are basically trying to graft a skin tissue which is exactly similar to that of a human skin so these are all live layers correct you basically have bioengineering scaffolding events happening over here over which you basically plant cells and basically grow that cells thereby they technically looks like that of a human skin so these are the histological sections from that technically looks pretty much same only thing is that when you place them on the individual who is having chronic wounds it should integrate with that correct it should integrate so integration is still an issue but these type of tools are available and these type of tools emerge just because of bioengineering faculties like you correct so it is a really really fascinating area you can load various drugs to it you can load various other molecules to it so on and so forth so my discussion today is a little bit different from what we have discussed so far our goal is to discuss something known as light therapy or the low level laser or low level light therapy for chronic non healing wounds and again you know the light therapy situation is there or the use of light as a therapeutic modality is being there for time immemorial so you can see individuals using light as a source of healing for various purposes in various civilizations and pretty much you are pretty much familiar about this electromagnetic spectrum with respect to the therapeutic approach there are two windows over here one is at the far right or the near infrared range versus that of the blue wavelengths that are mainly used for decreasing the biofilm burden as well as the infectious burden of the wound so different wavelengths are being used or played by different investigators depending upon what type of purpose you are expecting over there so even when you use low level light therapies you can use a laser source versus an LED source and probably you know the difference between these better than me so monochromaticity coherence, collimation so on and so forth are some of the characteristic features that differentiates laser beam versus that of an LED light source and it is being extensive and based in the context of light therapy both LED as well as lasers are equally used for various purposes so what I am trying to discuss here is something known as a near infrared photo biomodulation so you can see that vocabulary photo biomodulation you are modulating cellular effects using photons when I say modulating you are increasing a particular function of SL or decreasing the particular function of SL so you are modulating the cellular functions using light energy so in this particular case we are using near infrared photons so it is a low energy photon irradiation by monochromatic light in the particular range over there and it can be achieved by using laser sources versus that of LED light sources and as a result of this irradiation you can have tissue repair happening you can quench the inflammatory response you can have an altered profile for pain you can alter edema you can have various type of pain related profile treated for this treated using this modality but Is that directly affecting transcription back? Yeah that is the whole point so we will see that in one of the slides in the one of the slides coming after this so as a result of low level light therapy you end up altering the cellular apoptosis, proliferation migratory events as well as the ability of the cell to attach one to other so these are some of the factors that are either up regulated or down regulated it can happen both ways either up regulated or down regulated as a result of it so the reason why and this is not a new science this has been there for many decades at this point of time and the reason why you are able to use light as a source to modulate the cellular function is because you have photo acceptors in various cellular compartments and one widely accepted photo acceptor is cytochromoxidase of your electron transport chain so cytochromoxidase is an established photo acceptor in that particular near infrared range and these are being proved by various emission absorption emission spectral studies using isolated cytochromoxidase and irradiating that with light and getting the peaks on and so forth so you generally get peaks based upon as you can see over here you can see you can get peaks in that particular range as well as you can have altered activity so on and so forth so the goal here is that cytochromoxidase is a very at this point of time again very well established photo acceptor molecule for this particular wavelength that we are discussing over here and again I am not going into the details of the cellular mechanisms over here there are copper A copper B senders that are till electrons which indirectly affects the electron transport chain thereby ATV generation is upregulated ATV by itself is a signaling molecule you start producing more free radicals free radicals itself is a signaling molecule that can go downstream to affect various other signaling pathways as well that is again described over here the question over there was whether it affects the gene transcription obviously yes there are a lot of literature evidence that basically explains the upregulation of various transcript terms depending upon what you are basically investigating over there so the gene transcription events happen as a result of the photons interacting with the cytochromoxidase and on the right what you are seeing again gene expression various transcription factors similar to that of NF Kappa B AP1 so on and so forth basically dictating these processes and again as I have discussed before ATV by itself can be a signaling molecule within the cell free radicals can be a signaling molecule within the cell these are all outcomes of an exposed event to this particular wavelength that is happening and again interestingly you basically have an optical window with a much more broader interaction with that of the physiological molecules you can see a window over there where there is much more disturbance that is happening for that particular wavelength so this is a range this is not an exact wavelength that you can pick and there are individuals who pick exact wavelength to work with their hypothesis but my personal thought is that it's a range that basically functions to achieve this goal and again tissue penetration is again a huge issue so these days low-level light therapy is being extensively used for transcranial applications transcranial applications for dementia various type of traumatic injuries so on and so forth and there are a lot of very well established publications out there that basically that basically explains the clinical outcomes in a positive way because of irradiation transcraniality so it has to penetrate the skull and basically reaches certain compartments of the brain to basically achieve that particular goal and there are fMRI studies there are various other fascinating imaging studies that goes hand-in-hand with that so you can see the depth of penetration as well as some of the events that is happening as a result of this exposure as we have discussed in the context of wound healing exclusively you have extracellular matrix production happening or the collagen synthesis happening matrix metalloprotease plays a significant role you alter the vascular perfusion you decrease apoptosis you cause the proliferation of fibroblasts as well as keratinocytes and so on and so forth so all the things that we have discussed earlier that leads to a step-by-step step-by-step mechanism of wound healing will be affected in one way or other I am not absolutely saying that when you flash light everything is going to happen that's not the case here certain events are upregulated certain events are downregulated and again everything depends upon the dosage of the light itself so similar to pharma-sutics it's like a photosuitical approach so similar to the pharma-sutical molecules you have a biphasic response curve the Arnold shoes load that probably you are familiar as well so similar to that this has a biphasic curve to that particular event as well so similar to pharma-sutical photosuiticals are highly highly of clinical significance at this point of time so the device that we mostly use are something known as a warp device and again this is a NASA spin-off probably a few decades back and this is manufactured by a company in Bonville, Wisconsin so you can see the wavelength specification as well as the characteristics of the spectral power and output from this particular diagram and the reason why we initially started using is because we had access to it and through my mentor I had access through so it's a hereditary anyone that got passed from one mentor to the other so I will wrap up the discussion here by showing some of the clinically relevant publications out that basically so don't get scared these are much more simpler forms of wounds so wounds gets really bad wounds gets really really bad so these are very simple forms of wounds very simple nature or phenotypes of wounds that you can see but in a clinical product you see much more worlds of situation so in the left panel what you are seeing is a wound that has been treated by the wavelength used here is 632 you can see that there is a difference from the wavelength that we have discussed before and obviously I believe in the range rather than picking a particular wavelength you can see the wound getting healed with time and the corresponding wound ulcer area plot over there and on the right panel what you are seeing is the control arm correct this is just from an example from a particular study that got published in 2015 so we did a pilot study based upon a CTSI grant actually my mentor was the lead author in that particular study the issue here was that when you are having spinal cord injuries the innervation to your extremities are compromised right so when your innervations are compromised you end up having a profile similar to that of neuropathy because you don't have sensation you are in the wheelchair to begin with but again you don't have sensation in your extremities as a result of which when you are having a wound it will never heal because sensation is required for wound healing purpose as well if you don't have sensation the wound is not going to heal at any given point of time so these individuals or these highly highly served veterans who are coming back from various war zones will end up having diabetic sorry foot ulcers in their extremities and we treated them with light as you see over there and with the light treatment what we are able to demonstrate was that there is a significant decrease in the wound area and this will be out in publication pretty soon we are finalizing some of the wound fluid analysis as well and the reason why I mentioned this particular study is to emphasize the fact that this is entirely different from diabetic foot ulcers so this is a chronic non-healing wound that happens in spinal cord injured veterans and we did this study at the VA over here so from our study over here we are demonstrating the fact that the healing is very much accelerated in these clinical situations as well and again there are multiple other studies out there which basically explains the signaling pathways involved and again depending upon your area of interest you start looking at a particular signaling pathway but there are thousands of pathways that can be investigated in that particular context so this is basically explaining this publication that came out this year and again this just got published basically I was looking at the jack stat pathway probably you are familiar about that pathway and you can see an up-regulation so activated stat propagates extracellar signals for gene transcription leading to cell proliferation as well as migration so this wavelength that they used was like 66 and again it's a huge debate with respect to the photo bio modulation field as well what exactly the so the individual who used 660 will claim that that is the one that works the individual who used 661 will claim that that is the one that basically works so there is huge debate that revolves around it and obviously the dosage associated with it the duration that goes hand in hand with the dosage all needs to be much more characterized in a particular clinical setting so you can see the jack as well as stat pathway is altered in this particular case creating a loop of epidermal growth factor as well as epidermal growth factor receptor mechanisms thereby the healing is made at a faster rate because it basically reflects the epidermal for example if you are introducing or if you are if you are basically introducing epidermal growth factor into a wound technically should supposed to heal because that is a growth hormone so not a growth hormone growth factor exactly so there are many other growth factors that can be used in that practice as well so before I conclude there are some future directions that we plan to move ahead as well so using various and again seabra fish model for wound healing is pretty new the drosophilia model for wound healing is pretty new for so depending upon available resources we have we plan to do more investigations understanding the cellular mechanisms using newer animal models dosage characterizes very important in the field a lot of things that need to be characterized with the dose and again that is true with the source as well whether you are using a laser source versus that of a LED light source immunology of wound healing is again really really a complex area to look and again novel light related interactions or technologies when I am preparing for this particular talk I could see that there are novel films as well as products similar to that of creams that you can use which can be excited photo dynamically with particular wavelength of light and we obviously need larger clinical trials and I have immense interest in using various scaffolding materials similar to that of nanofibro scaffolds nanomaterials especially tagging nanomaterials to various growth factors and immune modulators that can alter the profile of healing in those wounds nanomaterials a huge area that I am really interested in it you can basically tag nanomaterials with growth factors so that goes hand in hand and obviously when you want to deliver a material you need a scaffold to an extent so various type of scaffolds can be used for achieving that particular goal as well so there are a lot of plans that we are and we do a lot of experiments together as well so most of the experiments are performed at the level of rodent animal models even though we do clinical trials in humans as well but we want to elaborate the sample size we want to increase the type of animal models that we are using for our studies as well so with that I will conclude my discussion and if you have any questions I will take questions from here thank you oh thanks if there are questions I can pass the microphone yeah sure just curious what type of wounds can be healed with these light therapy techniques what type of wounds so when you say what type of wounds so those publications that are out are all chronic non healing wounds correct when I say chronic non healing wounds those are wounds that is not going to heal in a normal fashion correct they stay there and because of the comorbid issues that goes hand in hand with that if you are not taking care of it it will never heal so that wound will stay there and it becomes larger and larger and larger finally you have to cut your leg I mean in terms of intensity of the wound so it can be of oh you are asking how how serious it can be like the minor wounds versus any sort of complex wound topology that you can expect as well if it is a really large wound in your anterior or posterior area large surface area you can and again it depends upon the surface area that you are available that you have available with respect to the light source as well that again is a challenging thing designing a larger light source for achieving this particular goal and just one more question I am curious about so for the pressure ulcer, diabetic pressure ulcer which steps of the wound process is more effective so with the diabetic foot ulcers and PRU or pressure ulcers are two different things right and it can go hand in hand as well you can have diabetes and can get pressure ulcers that's a different story versus you can have diabetes foot ulcers by itself so to have pressure ulcers first of all most of the time you are immobilized you are in bed for an extended period of time so what steps are involved in the hemostasis versus inflammation versus proliferation with the diabetes foot ulcers almost all events are compromised pressure ulcers also almost all events are compromised you start compromising all those events that we have discussed in a step by step fashion that leads to chronic wounds so you can't say that this is because of and again there are disorders just because of hemostasis irregularity or just because of inflammation irregularity but the point here is that if one is done the others things also fall off correct yep thanks have you guys do you have data on how this affects subcutaneous wounds for post surgery or deep cuts gashes and things the scar tissue formation is different we haven't done that by ourselves but if you read the literature there are tons of evidence for it there is a substantial difference in the amount of scarring that formed it's really interesting so if you heal with less scarring that's a big thing if you are healing a wound with a less scarring that's a big thing as well and again I'm not discussing and there are a lot of other areas that are of huge significance in your particular context as well novel biomaterials loaded with various biological molecules nanomaterials again huge area of huge significance at this point of time correct and on top of all that another area that I'm really curious about is to have exact measurements of wound topology so the one that you are seeing here is an example of very low grade wounds so if I show you the massive nature of the wounds it's really hard to quantify the topology of the wound and when we when we discussed about wound healing process it has to come out in a three-dimensional fashion that has come up from inside out so most of the time if even if you look at nearby wound clinics over here you don't have a very reliable tool through which you basically get or you can gauge the characteristics of the wound there are commercial products out there but really expensive to buy and use as well thank you very much I have a question for you so these wounds are very complex the characteristic of which is different but on average the photobiomodulation would heal like in what percentage of these basically wounds what all different types on average and does it depend on the dosage and the duration you mentioned that there's always this basically discussion what type of laser and what's the dosage and what's the duration to use but is there like an average number out there that photobiomodulation is effective like 75% or 85% in terms of wound healing can you give us the number so those type of numbers are probably out there but I'm not familiar about those numbers so the question here is whether if you have 10 different wounds whether 50% of them can be healed versus 75% of them I'm exactly not sure about the number out there probably there should be some numbers out there with respect to that and the debate always revolves around for example if I'm an investigator who is using 670 versus another investigator who uses 660 he or she will try to establish the fact that 660 works better than 670 but I am always of the thought that it's a range rather than a particular wavelength that does the magic over here and when you are exposed to UV light it's not the particular wavelength of UV that you are exposed to it's a range of wavelength that you are exposed to that creates the physiological consequence of UV Is there any publications talking about that range and the effectiveness do you see a change in regulation from you know is it 10 nanometers? There are a lot of comparative wavelength studies that has been done as well so the one that I thought of putting that as well so one study that was recently published was comparing for example 630 versus 670 versus 810 versus 870 so on and so forth doing that particular I should have put that so doing that particular studies they were able to have an relative betterment with a particular wavelength when compared to that probably because of that particular wavelength is much more redundant in interacting with the cytochromoxidase something like that would have been the basic reason for that Those type of studies are out there as well Okay let's thank her Oh thank you very much