A Three Species Model to Simulate Application of Hyperbaric Oxygen Therapy to Chronic Wounds

Chronic wounds are a significant socioeconomic problem for governments worldwide. Approximately 15% of people who suffer from diabetes will experience a lower-limb ulcer at some stage of their lives, and 24% of these wounds will ultimately result in amputation of the lower limb. Hyperbaric Oxygen Therapy (HBOT) has been shown to aid the healing of chronic wounds; however, the causal reasons for the improved healing remain unclear and hence current HBOT protocols remain empirical. Here we develop a three-species mathematical model of wound healing that is used to simulate the application of hyperbaric oxygen therapy in the treatment of wounds. Based on our modelling, we predict that intermittent HBOT will assist chronic wound healing while normobaric oxygen is ineffective in treating such wounds. Furthermore, treatment should continue until healing is complete, and HBOT will not stimulate healing under all circumstances, leading us to conclude that finding the right protocol for an individual patient is crucial if HBOT is to be effective. We provide constraints that depend on the model parameters for the range of HBOT protocols that will stimulate healing. More specifically, we predict that patients with a poor arterial supply of oxygen, high consumption of oxygen by the wound tissue, chronically hypoxic wounds, and/or a dysfunctional endothelial cell response to oxygen are at risk of nonresponsiveness to HBOT. The work of this paper can, in some way, highlight which patients are most likely to respond well to HBOT (for example, those with a good arterial supply), and thus has the potential to assist in improving both the success rate and hence the cost-effectiveness of this therapy

Role of wild-type estrogen receptor-β in mitochondrial cytoprotection of cultured normal male and female human lens epithelial cells

The influence of sexual category as a modifier of cellular function is underinvestigated. Whether sex differences affect estrogen-mediated mitochondrial cytoprotection was determined using cell cultures of normal human lens epithelia (nHLE) from postmortem male and female donors. Experimental indicators assessed included differences in estrogen receptor-β (ERβ) isoform expression, receptor localization in mitochondria, and estrogen-mediated prevention of loss of mitochondrial membrane potential using the potentiometric fluorescent compound JC-1 after nHLE were exposed to peroxide. The impact of wild-type ERβ (wtERβ1) was also assessed using wtERβ1 siRNA to suppress expression. A triple-primer PCR assay was employed to determine the proportional distribution of the receptor isoforms (wtERβ1, -β2, and -β5) from the total ERβ message pool in male and female cell cultures. Irrespective of sex, nHLE express wtERβ1 and the ERβ2 and ERβ5 splice variants in similar ratios. Confocal microscopy and immunofluorescence revealed localization of the wild-type receptor in peripheral mitochondrial arrays and perinuclear mitochondria as well as nuclear staining in both cell populations. The ERβ2 and ERβ5 isoforms were distributed primarily in the nucleus and cytosol, respectively; no association with the mitochondria was detected. Both male and female nHLE treated with E2 (1 μM) displayed similar levels of protection against peroxideinduced oxidative stress. In conjunction with acute oxidative insult, RNA suppression of wtERβ1 elicited the collapse of mitochondrial membrane potential and markedly diminished the otherwise protective effects of E2. Thus, whereas the estrogen-mediated prevention of mitochondrial membrane permeability transition is sex independent, the mechanism of estrogen-induced mitochondrial cytoprotection is wtERβ1 dependent. Copyright © 2008 the American Physiological Society

Oxidized (non)-regenerated cellulose affects fundamental cellular processes of wound healing

In this study we investigated how hemostats such as oxidized regenerated cellulose (ORC, TABOTAMP) and oxidized non-regenerated cellulose (ONRC, RESORBA CELL) influence local cellular behavior and contraction of the extracellular matrix (ECM). Human stromal fibroblasts were inoculated in vitro with ORC and ONRC. Cell proliferation was assayed over time, and migration was evaluated by Live Cell imaging microscopy. Fibroblasts grown in collagen-gels were treated with ORC or ONRC, and ECM contraction was measured utilizing a contraction assay. An absolute pH decline was observed with both ORC and ONRC after 1 hour. Mean daily cell proliferation, migration and matrix contraction were more strongly inhibited by ONRC when compared with ORC (p < 0.05). When control media was pH-lowered to match the lower pH values typically seen with ORC and ONRC, significant differences in cell proliferation and migration were still observed between ONRC and ORC (p < 0.05). However, in these pH conditions, inhibition of matrix contraction was only significant for ONRC (p < 0.05). We find that ORC and ONRC inhibit fibroblast proliferation, migration and matrix contraction, and stronger inhibition of these essential cellular processes of wound healing were observed for ONRC when compared with ORC. These results will require further validation in future in vivo experiments to clarify the clinical implications for hemostat use in post-surgical wound healing

Fibronectin and perlecan expression in intact HAM and after various treatments.

<p>The results on fibronectin (A) and perlecan (B) are similar to other BM components. Only thermolysin and NaOH completely remove amniotic epithelium. Immunohistochemical staining of O.C.T.-embedded and sectioned HAM. Bar = 20 µm.</p

Cell removal by NaOH from cryopreserved HAM.

<p>A, phase contrast of cryopreserved and thawed out HAM showing a monolayer of amniotic epithelial cells. B, the same HAM stained with TB; all cells are stained. C, cotton swab rubbing of HAM leaves many amniotic epithelial cells behind. D, after 30 sec rub with 0.5 M NaOH-soaked cotton swab no cells are left. E, NaOH effectively removes cells from HAM (gray line shows the boundary of the rubbed zone). Bar in A–D = 50 µm; in E, bar = 100 µm.</p