Yanfu Han

Differentiation of human umbilical cord mesenchymal stem cells into dermal fibroblasts in vitro

Tissue-derived umbilical cord mesenchymal stem cells (UCMSCs) can be readily obtained, avoid ethical or moral constraints, and show excellent pluripotency and proliferation potential. UCMSCs are considered to be a promising source of stem cells in regenerative medicine. In this study, we collected newborn umbilical cord tissue under sterile conditions and isolated UCMSCs through a tissue attachment method. UCMSC cell surface markers were examined using flow cytometry. On the third passage, UCMSCs were induced to differentiate into dermal fibroblasts in conditioned induction media. The induction results were detected using immunofluorescence with a fibroblast-specific monoclonal antibody and real time PCR for type I and type III collagen. UCMSCs exhibited a fibroblast-like morphology and reached 90% confluency 14 to 18 days after primary culture. Cultured UCMSCs showed strong positive staining for CD73, CD29, CD44, CD105, and HLA-I, but not CD34, CD45, CD31, or HLA-DR. After differentiation, immunostaining for collagen type I, type III, fibroblast-specific protein, vimentin, and desmin were all strongly positive in induced cells, and staining was weak or negative in non-induced cells; total transcript production of collagen type I and collagen type III mRNA was higher in induced cells than in non-induced cells. These results demonstrate that UCMSCs can be induced to differentiate into fibroblasts with conditioned induction media and, in turn, could be used as seed cells for tissue-engineered dermis.

Microencapsulated VEGF gene–modified umbilical cord mesenchymal stromal cells promote the vascularization of tissue-engineered dermis: an experimental study

BACKGROUND AIMS Tissue-engineered dermis (TED) is thought to be the best treatment for skin defect wounds; however, lack of vascular structures in these products can cause slow vascularization or even transplant failure. We assessed the therapeutic potential of microencapsulated human umbilical cord mesenchymal stromal cells (hUCMSCs) expressing vascular endothelial growth factor (VEGF) in vascularization of TED. METHODS hUCMSCs were isolated by means of enzymatic digestion and identified by means of testing biological characteristics. hUCMSCs were induced to differentiate into dermal fibroblasts in conditioned induction media. Collagen-chitosan laser drilling acellular dermal matrix (ADM) composite scaffold was prepared by means of the freeze dehydration and dehydrothermal cross-linking method. hUCMSC-derived fibroblasts were implanted on composite scaffolds to construct TED. TED with microencapsulated VEGF gene-modified hUCMSCs was then transplanted into skin defect wounds in pigs. The angiogenesis of TED at 1 week and status of wound healing at 3 weeks were observed. RESULTS The collagen-chitosan laser ADM composite has a uniform microporous structure. This composite has been used to grow hUCMSC-derived fibroblasts in vitro and to successfully construct stem cell-derived TED. Microencapsulated VEGF gene-modified hUCMSCs were prepared with the use of a sodium alginate-barium chloride one-step encapsulation technology. Seven days after the transplantation of the stem cell-derived TED and microencapsulated VEGF gene-modified hUCMSCs into the skin defect wounds on the backs of miniature pigs, the VEGF expression increased and the TED had a higher degree of vascularization. Re-epithelialization of the wound was completed after 3 weeks. CONCLUSIONS Microencapsulated VEGF gene-modified hUCMSCs can effectively improve the vascularization of TED and consequently the quality of wound healing.

A novel model of burn-blast combined injury and its phasic changes of blood coagulation in rats.

ABSTRACT Burn-blast combined injury has a complex pathological process that may cause adverse complications and difficulties in treatment. This study aims to establish a standard animal model of severe burn-blast combined injury in rats and also to investigate early phasic changes of blood coagulation. By using 54 Wistar rats, distance from explosion source (Hexogen) and size of burned body surface area were determined to induce severe burn-blast combined injury. Thereafter, 256 rats were randomly divided into four groups (n = 64): blast injury group, burn injury group, burn-blast combined injury group, and sham injury group. Gross anatomy and pathological changes in lungs were investigated at 3, 24, 72, and 168 h, respectively. Blood was also collected for analyzing coagulation parameters as prothrombin time, activated partial thromboplastin time, and plasma levels of fibrinogen, D-dimer, antithrombin III, and &agr;2-antiplasmin from 0 to 168 h after injury. Severe burn-blast combined injury was induced by inflicting rats with a moderate blast injury when placing rats 75 cm away from explosion source and a full-thickness burn injury of 25% total body surface area. The rats with burn-blast combined injury had more severe lung injuries when compared with the other three groups. Pathological examination in the BBL group showed diffused alveolar hemorrhage, fluid filling, alveolar atelectasis, rupture and hyperplasia of partial alveolar septum, emphysema-like change, reduced capillary bed, and infiltration of extensive polymorphonuclear cells after injury. The blood of combined injured rats was in a hypercoagulable state within 24 h, shortly restored from 24 to 48 h, and rehypercoagulated from 48 to 72 h after injury. A secondary excessively fibrinolytic function was also found thereafter. The rat model of burn-blast combined injury was successfully established by simulating real explosion characteristics. Rats with burn-blast combined injuries suffered from more severe lung injuries and abnormal coagulation and fibrinolytic function than those induced by a burn injury or a blast injury component. Hence, a time-dependent treatment strategy on coagulation function should be emphasized in clinical therapy of burn-blast combined injury.

Clinical application prospect of umbilical cord-derived mesenchymal stem cells on clearance of advanced glycation end products through autophagy on diabetic wound

Nowadays, wound healing delay due to diabetes is considered to be closely related to the accumulation of advanced glycation end products (AGEs). Although mesenchymal stem cells (MSCs) exhibit positive effects on diabetic wound healing, related mechanisms are still not fully elucidated. It has been reported that MSCs can improve the activity of autophagy in injured tissues, thereby playing an important role in wound healing. The autophagy induced by MSCs may be beneficial to diabetic wound healing via removing AGEs, which provide new ideas for clinical treatment of diabetic wounds with the potential of broad application prospects. In this study, the current research situation and application prospect of umbilical cord-derived MSCs on the clearance of AGEs in diabetic wound were reviewed.