EGFL7-overexpressing epidermal stem cells promotes fibroblast proliferation and migration via mediating cell adhesion and strengthening cytoskeleton.

Epidermal growth factor (EGF)-like family members mediate a wide range of biological activities including cell proliferation and migration. Increasing evidence indicated that EGF plays an important role in the process of wound healing by stimulating fibroblast motility. The aim of this study was to see whether EGF-like domain 7 (EGFL7)-overexpressing epidermal stem cells (EGFL7-ESCs) would promote fibroblast proliferation and migration. We found that mRNA and protein levels of EGFL7 expression were significantly increased in EGFL7-ESCs. The protein expression of EGFL7 was significantly elevated in conditioned media (CM) of EGFL7-ESCs compared to ESCs CM or vector-ESCs CM. The cell count and cell viability of EGFL7-ESCs CM-treated fibroblasts were also significantly increased compared to control. In addition, EGFL7-ESCs CM-treated fibroblasts showed elevated migration compared with control. Moreover, the expressions of ß1-integrin, ß-tubulin, ß-actin, and Vimentin were increased, while that of E-cadherin was decreased in EGFL7-ESCs CM-treated fibroblasts. These results indicate that EGFL7-ESCs contribute towards promoting fibroblast migration through enhancing cell adhesion, strengthening cytoskeleton, and reducing intercellular aggregation. These findings suggest that the stimulating effect of EGFL7-ESCs on fibroblast proliferation and migration may provide a useful strategy for wound healing.

Effects of porcine acellular dermal matrix treatment on wound healing and scar formation: Role of Jag1 expression in epidermal stem cells.

Skin wound healing involves Notch/Jagged1 signaling. However, little is known how Jag1 expression level in epidermal stem cells (ESCs) contributes to wound healing and scar formation. We applied multiple cellular and molecular techniques to examine how Jag1 expression in ESCs modulates ESCs differentiation to myofibroblasts (MFB) in vitro, interpret how Jag1 expression in ESCs is involved in wound healing and scar formation in mice, and evaluate the effects of porcine acellular dermal matrix (ADM) treatment on wound healing and scar formation. We found that Jag1, Notch1 and Hes1 expression was up-regulated in the wound tissue during the period of wound healing. Furthermore, Jag1 expression level in the ESCs was positively associated with the level of differentiation to MFB. ESC-specific knockout of Jag1 delayed wound healing and promoted scar formation in vivo. In addition, we reported that porcine ADM treatment after skin incision could accelerate wound closure and reduce scar formation in vivo. This effect was associated with decreased expression of MFB markers, including α-SMA Col-1 and Col-III in wound tissues. Finally, we confirmed that porcine ADM treatment could increase Jag1, Notch1 and Hesl expression in wound tissues. Taken together, our results suggested that ESC-specific Jag1 expression levels are critical for wound healing and scar formation, and porcine ADM treatment would be beneficial in promoting wound healing and preventing scar formation by enhancing Notch/Jagged1 signaling pathway in ESCs.

[Treatment of deep partial thickness burns by a single dressing of porcine acellular dermal matrix].

OBJECTIVE: To explore the effect of one dressing of porcine acellular dermal matrix on deep partial thickness burns. METHODS: From January 1997 to January 2004, sixty-seven cases of deep partial thickness total burned surface area (TBSA) from 50% to 90% burn wound were treated by a single dressing of porcine acellular dermal matrix (the porcine acellular dermal matrix group). Ten cases of deep partial thickness burned patients with the same TBSA treated by exposure method served as the exposure method group. The healing time of the wound was observed. The patients were followed up for 3 months to 2 years, and the scar proliferation was observed. RESULTS: The deep partial-thickness wound would be healed without dressing change in the porcine acellular dermal matrix group, and the average healing time was (12.2 +/- 2.6) days. The average healing time of the exposure method group was (27.4 +/- 3.5) days. Follow up of the patients within 3 months to 2 years showed that scar proliferation in the porcine acellular dermal matrix group was much less than that in the exposure method group, even no scar proliferation was observed in some patients. CONCLUSION: Without tangential excision, autografting and dressing change, a single dressing of porcine acellular dermal matrix on deep partial thickness burn wound could shorten the healing time and inhibit scar proliferation.

Epidermal stem cells (ESCs) accelerate diabetic wound healing via the Notch signalling pathway.

Chronic, non-healing wounds are a major complication of diabetes. Recently, various cell therapies have been reported for promotion of diabetic wound healing. Epidermal stem cells (ESCs) are considered a powerful tool for tissue therapy. However, the effect and the mechanism of the therapeutic properties of ESCs in the diabetic wound healing are unclear. Herein, to determine the ability of ESCs to diabetic wound healing, a dorsal skin defect in a streptozotocin (STZ)-induced diabetes mellitus (DM) mouse model was used. ESCs were isolated from mouse skin. We found that both the mRNA and protein levels of a Notch ligand Jagged1 (Jag1), Notch1 and Notch target gene Hairy Enhancer of Split-1 (Hes1) were significantly increased at the wound margins. In addition, we observed that Jag1 was high expressed in ESCs. Overexpression of Jag1 promotes ESCs migration, whereas knockdown Jag1 resulted in a significant reduction in ESCs migration in vitro Importantly, Jag1 overexpression improves diabetic wound healing in vivo These results provide evidence that ESCs accelerate diabetic wound healing via the Notch signalling pathway, and provide a promising potential for activation of the Notch pathway for the treatment of diabetic wound.

[Porcine acellular dermal matrix in the treatment of deep partial-thickness burns in human].

OBJECTIVE: To investigate the possibility of treating deep partial-thickness burns by closed dressing of the wounds with porcine acellular dermal matrix (ADM) and evaluate the therapeutic effects. METHODS: We conducted a retrospective review of 128 cases of burn patients who received treatment with porcine ADM within the period from January 1998 to January 2002 in our hospital. Different procedures were adopted according to the degree of the burn injury. As for "fairly superficial" deep partial-thickness skin burns, after removing the necrotic epidermis and washing with 0.1 % benzalkonium bromide, the wound was covered with porcine ADM pretreated with povidone-iodine and then bandaged with cotton gauze and bandages. In cases of "fairly deep" deep partial skin thickness burns, eschar excisions as deep as to expose parabiotic lamina were performed prior to dressing the wounds in the same manner as described above. RESULTS: All the patients were successfully treated with satisfactory clinical results. CONCLUSIONS: Porcine ADM is feasible as an efficient dressing material for deep partial-thickness burns, which may promote epithelialization in the wounds and help stabilize the patients' condition during burn shock stage to reduce the complications and shorten the treatment courses.

An improved method for the isolation and culture of rat epidermal stem cells.

The management of burns and injuries using novel treatment strategies involving epidermal stem cells (ESC) requires a better understanding of the biology of these cells, in particular, their isolation and the maintenance of their unique characteristics in culture. The purpose of this study was to describe an improved method for isolating putative ESC from fetal rat skin and to maintain them long term in culture. Single ESC suspensions were obtained from fetal rat skin by enzyme digestion containing 0.5% neutral protease. The target cells were harvested by rapid adherence on type IV collagen plates and were cultured in complex DMEM. After primary isolation, cells were continuously cultured in K-serum free medium. After reaching 70-80% confluence, the cells were digested with 0.25% trypsin at 37°C for 5-10 minutes, and passaged at a ratio of 1:2. The cultured ESC showed good growth, resulting in cell viability of over 98%. Four days later, clones containing 100-200 cells were detected, showing cobblestone-like characteristics. The rapidly adherent cells were positive for keratin 15, 19 and P63. Eighty three percent of cells expressed ß1 integrin. The growth-curve showed that the rapidly adherent cells were in the exponential growth phase. The protocol described in this paper provides a simplified and effective method to isolate and maintain long-term culture of epidermal stem cells from fetal rat skin. This method should be valuable for isolating and studying ESC from various transgenic rat lines that are currently available.

[Clinical application of xenogenic (porcine) acellular dermal atrix (ADM) in scar treatment].

OBJECTIVE: To investigate the role of xenogenic (porcine) ADM as dermal substitute in scar treatment. METHODS: After scar excision, the wounds were covered with composite grafts of DR procine ADM and autologous thin split-thickness grafts in one stage or in two stages. RESULTS: 22 out of 47 cases were treated in two-staged procedure. After the ADMs were applied to the wound, the autologous thin split-thickness grafts were implanted 7 days later. 25 cases were treated in one-staged procedure. The survival rates of composite grafts were (88.3 +/- 3.7)% for subcutaneous recipient bed and (89.7 +/- 3.4)% for deep fascia recipient bed in group with two-staged procedure, compared with (92.5 +/- 4.1)% and (93.2 +/- 5.2)%, respectively, in group with one-staged procedure. Early after grafts taken, the grafts had a pink colour and smooth surface. The patients were followed up for 90 days at most. The survived composite grafts were durable, elastic, smooth and soft with good function and appearance like normal skin. They could even be pinched up. The scar along the edge of the grafts was slightly hypertrophic. CONCLUSIONS: The survival rate of composite graft is higher in patients with one-staged procedure. The elasticity and textural of the taken grafts are better on subcutaneous recipient bed than on deep fascia recipient bed, though the function has no difference. Xenogenic (porcine) ADM can be an optimal dermal substitute for wound coverage after scar excision.