M. Tech. / Phototobiomodulation (PBM), also known as low level laser therapy (LLLT) or photobiostimulation, is a non-invasive form of therapy that utilizes low intensity laser light or irradiation to provide healing. However, in order for healing to be successful certain laser parameters need to be taken into consideration i.e. fluence (dosage), wavelength and power density. Laser therapy has been used for various medical applications and fields. Multiple cytokines and growth factors are involved in wound healing including Interleukin (IL)-1, IL-6 and Tumour Necrosis Factor alpha (TNF- a). In diseased state(s) such as diabetes mellitus (DM) or psoriasis, these growth factors or cytokines are either found elevated or decreased depending on various factors and for abnormally prolonged periods. However, inflammatory cytokines are usually elevated. Phototherapy has been reported to accelerate wound healing, attenuate pain and cease inflammation. However, the effect of phototherapy on cytokine modulation has not been explored extensively, especially under various stress mechanisms. Furthermore, the pathway that laser irradiation induces on modulated pro-inflammatory cytokines has not been clearly elucidated as scientists typically report on the up- or down-regulated expression of cytokines. Numerous authors have reported on the efficacy of laser irradiation to enhance the rate of wound healing and proliferation in normal and diabetic cells or tissue; however, literature that has demonstrated the latter on hypoxic insulted cells is inadequate. In this study hypoxic insult was induced as it is one of the factors that usually prolong the healing process in diabetic wounds. Prior to commencing with the main study, a pilot study was done to exclude the effect of osmotic pressure on cells grown in media containing additional glucose, and thus simulating a diabetic model iv in vitro. Mannitol was used as a control since it is not absorbed by the cells. The study involved four groups namely: normal, normal wounded, mannitol wounded and diabetic wounded cells with each group having a non-irradiated control. Mannitol wounded and diabetic wounded cells had a final concentration of 30 mM mannitol and glucose respectively. A wavelength of 636 nm at a fluence of 5 J/cm2 was used on day 1; experiments were repeated four times and all tests were done in duplicate. Cellular responses (Trypan Blue, adenosine triphosphate (ATP) and lactate dehydrogenase (LDH)) and morphological changes were assessed after 1 h incubation post-irradiation in both irradiated and non-irradiated cultures.

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Yes / Mice represent the most commonly used species for preclinical in vivo research. While incisional and excisional acute murine wound models are both frequently employed, there is little agreement on which model is optimum. Moreover, current lack of standardization of wounding procedure, analysis time point(s), method of assessment, and the use of individual wounds vs. individual animals as replicates makes it difficult to compare across studies. Here we have profiled secondary intention healing of incisional and excisional wounds within the same animal, assessing multiple parameters to determine the optimal methodology for future studies. We report that histology provides the least variable assessment of healing. Furthermore, histology alone (not planimetry) is able to detect accelerated healing in a castrated mouse model. Perhaps most importantly, we find virtually no correlation between wounds within the same animal, suggesting that use of wound (not animal) biological replicates is perfectly acceptable. Overall, these findings should guide and refine future studies, increasing the likelihood of detecting novel phenotypes while reducing the numbers of animals required for experimentation.

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In humans, the epidermis is the main site for the synthesis of Vitamin D3 (cholecalciferol) from 7-dehydrocholesterol. Cholecalciferol undergoes further hydroxylation in the liver and kidney to produce the active form of the circulating hormone 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). In target cells, 1,25(OH)2D3 interacts with the specific intracellular vitamin D receptor (VDR), a member of the nuclear receptor superfamily. However, epidermal keratinocytes, in addition to being target cells, have enzymes required for autocrine production of 1,25(OH)2D3. They can convert cholecalciferol to 1,25(OH)2D3 via 25-hydroxylase (CYP2R1) and 1α-hydroxylase (CYP27B1). Another enzyme, 24-hydroxylase (CYP24A1), regulates local levels by inactivating 1,25(OH)2D3. While recent studies have shown that absence of VDR or 1,25(OH)2D3 impairs formation of granulation tissue during wound healing in mice, little is known about the autocrine and paracrine regulation of biologically active vitamin D3 by human dermal fibroblasts during cutaneous wound healing. Primary cultures of human keratinocytes and fibroblasts expressed VDR and all the cytochrome enzymes necessary for autocrine production of vitamin D. The relative expression of VDR mRNA was higher in dermal fibroblasts than donor-matched keratinocytes. In contrast, epidermal keratinocytes had a higher mRNA expression of vitamin D3 metabolising enzymes. A scratch wound assay confirmed that 1,25(OH)2D3 stimulated keratinocyte migration, but paradoxically inhibited fibroblast migration as early as 4h, yet neither cholecalciferol nor 25-hydroxyvitamin D3 had any effect. VDR knockdown using small interfering RNA (siRNA) abolished the inhibitory effect of 1,25(OH)2D3 on fibroblast migration, demonstrating the requirement for the VDR in this response. Immunofluorescent staining revealed that 1,25(OH)2D3 increased nuclear VDR protein expression, without a corresponding increase in VDR mRNA transcription only in mechanically wounded dermal fibroblasts, indicating activation of the receptors. Incubation with either 1,25(OH)2D3, cholecalciferol or 25(OH)D3 up-regulated CYP24A1 transcription. This response was most pronounced with 1,25(OH)2D3, suggesting a tightly regulated feedback control on 1,25(OH)2D3 bioavailability within the dermis. In addition, cholecalciferol also increased CYP2R1 and CYP27B1 mRNA expression in scratched dermal fibroblasts, providing evidence for autocrine regulation of 1,25(OH)2D3 by dermal fibroblasts. Expression of α-SMA protein was up-regulated in cultured dermal fibroblasts following scratching, which was down-regulated in the presence of 1,25(OH)2D3. These observations suggest that 1,25(OH)2D3 may restrict differentiation of wounded dermal fibroblasts into pro-fibrotic myofibroblasts. 1,25(OH)2D3 also down-regulated MMP-2 secretion and collagen type I to III ratio in scratched dermal fibroblasts. Using a human ex vivo wound healing model, it was demonstrated that 1,25(OH)2D3, but not cholecalciferol, stimulated the rate of wound closure. In summary, this study has confirmed that human dermal fibroblasts express the transcriptional machinery for autocrine production of 1,25(OH)2D3, and a higher VDR expression suggests they are more responsive than keratinocytes. Changes in CYP and VDR expression in the presence of cholecalciferol, 25-hydroxyvitamin D3 or 1,25(OH)2D3 indicate fine-tuning of the bioavailability of vitamin D in the dermis after wounding. Down-regulation of α-SMA, MMP-2 secretion and the collagen type I to III ratio by 1,25(OH)2D3 highlight an important role for 1,25(OH)2D3 in modulating wound healing and the scarring process.

The purpose was to objectively measure the rate of healing of equine distal limb wounds when a 10% Natural Proprietary Compound (NPC) was compared to a topical antibacterial cream (1% silver sulfadiazine- SSD). Five horses had two wounds measuring 6.25cm2 created on the dorsomedial aspect of each limb. Two contralateral limbs were randomly chosen to be bandaged and the other two limbs were un-bandaged – with one limb of each group being treated with either NPC or SSD. On each limb the most proximal wound was left without topical treatment to act as a control. There was no significant difference between SSD and the compound evaluated in this study when either perimeter or area was assessed. Control wounds were significantly smaller than those treated with an ointment regardless of other variables, giving rise to a proposed location effect. Bandaging by day was significant for the time period approximating 2-5 weeks.

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