Skin regeneration in deep second-degree scald injuries either by infusion pumping or topical application of recombinant human erythropoietin gel

Abstract

Large doses of recombinant growth factors formulated in solution form directly injected into the body is usual clinical practice in treating second-degree scald injuries, with promising results, but this approach creates side effects; furthermore, it may not allow appropriate levels of the factor to be sensed by the target injured tissue/organ in the specific time frame, owing to complications arising from regeneration. In this research, two delivery methods (infusion pumping and local topical application) were applied to deliver recombinant human erythropoietin (rHuEPO) for skin regeneration. First, rHuEPO was given in deep second-degree scald injury sites in mice by infusion pump. Vascularization was remarkably higher in the rHuEPO pumping group than in controls. Second, local topical application of rHuEPO gel was given in deep second-degree scald injury sites in rats. Histological analysis showed that epithelialization rate was significantly higher in the rHuEPO gel-treated group than in controls. Immunohistochemical studies showed that the rHuEPO gel-treated group showed remarkably higher expression of skin regeneration makers than the control group. An accurate method for visualization and quantification of blood vessel networks in target areas has still not been developed up to this point, because of technical difficulties in detecting such thin blood vessels. A method which utilizes a series of steps to enhance the image, removes noise from image background, and tracks the vessels edges for vessel segmentation and quantification has been used in this study. Using image analysis methods, we were able to detect the microvascular networks of newly formed blood vessels (less than 500 μm thickness), which participate in the healing process, providing not only nutrition and oxygen to grow tissues but also necessary growth factors to grow tissue cells for complete skin regeneration. The rHuEPO-treated group showed higher expression of stem cell markers (CD 31, CD 90, CD 71, and nestin), which actively contribute to in-wound-healing processes for new hair follicle generation as well as skin regeneration. Collectively, both rHuEPO group pumping into the systemic circulation system, and injection into the local injury area, prompted mice and rats to form new blood vessel networks in scald injury sites, which significantly participate in the scald healing process. These results may lead to the development of novel treatments for scald wounds.

Therapeutic strategies for enhancing angiogenesis in wound healing

“…The hormone erythropoietin (EPO) is another non-growth factor protein that has been shown to increase angiogenesis [140][141][142][143]. In second-degree burn injury model where a substantial portion of the original vasculature is damaged or lost completely, mice and rats treated with topical application or infusion of EPO displayed rates of angiogenesis that were significantly increased over the control that did not receive EPO [140]. Further, wound closure rates in the rats treated with EPO were accelerated over the control, with the wounds on average 98.8% closed by day 7.…”

“…Accelerates wound healing, promotes keratinocyte migration, increases angiogenesis Mice/Rats [136][137][138] Erythropoietin Delivery increases the rates of neovascularization and increases levels of PECAM-1 + cells at the wound site Mice/Rats [140][141][142][143] hGH Increases re-epithelialization, increases angiogenesis, and increases infiltration of Tlymphocytes Diabetic Rats [325,326] Syndecan-4 Enhances the revascularization, wound closure, and angiogenesis in response to treatment with FGF-2 and PDGF-BB ob/ob Mice/Rats [159] Glypican-1 Increases revascularization in hind limb ischemia model and increases FGF-2 activity in endothelial cells ob/ob Mice [48] SDF-1 Promotes recruitment of endothelial progenitor cells and anti-inflammatory monocytes. Helps to accelerate the wound healing process and promotes bMSC migration to the wound site.…”

Re-epithelialization of adult skin wounds: Cellular mechanisms and therapeutic strategies

“…The administration of EPO during skin wound healing is most likely based on its cytoprotective, proangiogenic, anti-apoptotic, and anti-inflammatory effects [238]. Re-epithelialization with hair follicle development at the injury site has also been observed in full-thickness burns upon local or systemic EPO administration [239][240][241].…”

A Randomized Controlled Trial: Regenerative Effects, Efficacy and Safety of Erythropoietin in Burn and Scalding Injuries

“…EPO and EPO-receptor synthesis and its anti-apoptotic, pro-angiogenic, pro- regenerative, anti-inflammatory, immunomodulatory and hypoxia/ischemia protective effects have been described in many tissues and organs ( Brines and Cerami, 2008 ; Minnerup et al, 2009 ; Solling, 2012 ; Günter et al, 2013b ). Previous publications using rodent models have described faster wound healing, higher quality of scars, prevention of secondary burn progression, higher levels of stem cell markers and higher amount of newly formed blood vessels in burn and scalding injuries or other wound models ( Galeano et al, 2006 ; Tobalem et al, 2012 ; Giri et al, 2015 ). The erythropoietic response to EPO is markedly decreased in thermally injured patients ( Still et al, 1995 ).…”