Daping Yang

Local delivery of adipose-derived stem cells via acellular dermal matrix as a scaffold: a new promising strategy to accelerate wound healing.

Wounds, characterized by leading to a loss of integrity of the skin and a major cause of morbidity and mortality, are common challenges encountered in plastic and reconstructive surgery. The primary goals of treatment are rapid closure, restoration of function, and aesthetical satisfaction. Adult stem cells may provide new strategies to treat cutaneous wounds because of their prolonged self-renewal capacity and ability to differentiate into various tissues. In the past five years, some researches discovered bone marrow mesenchymal cells (BMSCs) could accelerate wound healing. However, there exist several disadvantages of BMSCs mainly including the limitation of the obtainable amount and the impairment of their differentiation abilities with the increasing age. Due to the limitation of BMSCs in clinical application, we turn to consider adipose-derived stem cells (ASCs) as seeding cells in tissue repair for their own advantages. ASCs could not only possess capacity to differentiate into various lineages under appropriate conditions, but also release angiogenic factors that stimulate angiogenesis in ischemia injury models. Here we propose the hypothesis that ASCs locally delivered via acellular dermal matrix as a scaffold would enhance wound healing through both differentiation into endothelial and epithelial cells and production of angiogenic growth factors in cutaneous wounds. Furthermore, ASCs seeded acellular scaffold can be believed to offer more benefits for introducing stem cells to the local ischemia environment as it provides a framework for the support of their regenerative capacity. Therefore, if the hypothesis is proved to be practical, it might represent a novel therapeutic approach and enhance cutaneous wound healing more effectively.

MicroRNA-21 affects proliferation and apoptosis by regulating expression of PTEN in human keloid fibroblasts.

Background: MicroRNAs (miRNAs) are small noncoding RNA molecules that regulate gene expression in the progress of proliferation, differentiation, and apoptosis. A keloid is considered to be a type of benign tumor. The exact contribution of miRNAs in keloid fibroblasts remains largely unknown. Methods: Loss and gain of function was used by transfecting the keloid fibroblast cells with chemically synthesized oligonucleotides complementary to microRNA-21 (miR-21). Expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in keloid tissues and adjacent normal skin tissues were investigated by quantitative real-time polymerase chain reaction and Western blot assay. Moreover, cell apoptosis and proliferation were checked in keloid cells, and related proteins were determined by Western blot assay. Results: MiR-21 inhibitor and mimic transfection changed the apoptosis and DNA synthesis. Of the 23 paired samples analyzed, expression of PTEN was low in keloid tissues relative to adjacent normal skin tissues. Cells showed an inverse correlation between miR-21 and PTEN protein after transfection. In addition, cell proliferation was increased when normal skin fibroblasts were transfected with miR-21 mimics. It is worth noting that the expression of phosphorylated AKT decreased to relatively low levels after miR-21 inhibitor treatment. Conclusions: This in vitro study demonstrates important interactions among miR-21 expression, keloid fibroblast apoptosis, cell proliferation, and some related proteins. These findings may provide some hints toward effective applications of miR-21 as a therapy target for keloids.

Targeted delivery of adipose‐derived stem cells via acellular dermal matrix enhances wound repair in diabetic rats

Cell‐based therapeutic intervention has emerged as a new approach to accelerate wound closure. Adipose‐derived stem cells (ASCs), as a fascinating cell source, have received much attention in tissue repair and regeneration. In this study we evaluated the potential of acellular dermal matrix (ADM) scaffold serving as a carrier for the delivery of ASCs and investigated its therapeutic effects on wound healing. First, ASCs were isolated and characterized for multidifferentiation potential. ASCs–ADM grafts were then prepared, and ADM scaffold was shown to support the in vitro growth and proliferation of ASCs. Next, we analysed paracrine factors in conditioned medium and found that ASCs–ADM grafts secreted various cytokines, including VEGF, HGF, TGFβ and bFGF. Moreover, ASCs–ADM conditioned medium notably stimulated the migration and proliferation of fibroblasts. In vivo, we established an excisional wound model in diabetic rats which received phosphate‐buffered saline (PBS), ADM or ASCs–ADM grafts, respectively. Our results demonstrated that implantation of ASCs–ADM significantly enhanced tissue regeneration and increased epithelialization, resulting in accelerated wound closure. Immunofluorescence analysis further indicated that capillary density was evidently increased in the ASCs–ADM group compared with the control or ADM group. In addition, western blot analysis showed that ASCs–ADM significantly increased the expression of angiogenic factors, which was consistent with in vitro data. Taken together, our results suggest that targeted delivery of ASCs via ADM scaffold accelerate diabetic wound healing through a paracrine mechanism, with enhanced granulation tissue formation and increased re‐epithelialization and neovascularization. Copyright

Hypoxia preconditioning enhances the viability of ADSCs to increase the survival rate of ischemic skin flaps in rats.

Use of a skin flap has been a common technique in reconstructive surgery for more than five decades. However, partial necrosis of its distal end is still a serious postoperative complication. Many theories about this problem have been proposed, including deficient blood supply, which is the most accepted theory. In this study we demonstrated that hypoxic preconditioning enhanced the viability of adipose-derived stem cells (ADSCs) in vivo and improved their ability to increase the survival rate of ischemic skin flaps in rats. Seven days after flap elevation, the flap survival rate in the hypoxic preconditioned ADSC group was higher than that in the control group. Moreover, histological examination showed that more ADSCs survived in flaps treated by hypoxic preconditioning. Vascular density in the hypoxic preconditioned ADSC group was 30–90xa0% greater than that in the control group. In addition, the expressions of vascular endothelial growth factor and hypoxia inducible factor-1α (HIF-1α) were higher in the hypoxic preconditioned ADSC group than in the control group (pxa0<xa00.05). This enhancive phenomenon reached its highest level at the precondition times of 3 and 7xa0days in the hypoxic preconditioned ADSC group. We conclude that hypoxia preconditioning effectively enhances the viability of ADSCs to increase the survival rate of ischemic skin flaps. Furthermore, 3xa0days is the optimal preconditioning time point.Level of Evidence IIThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Establishing a new orthotopic composite hemiface/calvaria transplantation model in rabbits.

Background: Composite tissue allograft transplantation provides a better reconstructive option for patients who suffer from extensive craniomaxillofacial deformities. However, there is a lack of sufficient experimental data including anatomical and immunologic aspects in larger animals. The purpose of this study was to develop a new orthotopic composite hemiface/calvaria transplantation model in rabbits with which to estimate the feasibility of composite tissue allografts. Methods: A total of 36 rabbits were studied. The anatomical features were explored in six rabbits. Group I (n = 6) represented the autograft group. In the allograft control group (group II, n = 12) and the treatment group (group III, n = 12), orthotopic composite hemiface/calvaria allotransplantations were performed from Dutch to Japanese White rabbits. Recipients in the treatment group received low-dose cyclosporine A/prednisone combination therapy. Evaluation methods included clinical inspection, histologic analysis, immunohistochemistry, and radiography. Results: The animals in the autograft group survived indefinitely. Four of six nontreated allografts were rejected within 7 to 10 days. In the treatment group, five of six recipients showed no signs of rejection up to the endpoint of the study. Only one recipient died as a result of anorexia, on day 18. The histologic outcomes were well correlated with clinical inspection. Bone biopsy specimens at posttransplant days 7 and 120 revealed viable bone. Radiologic grade at day 120 showed no significant difference between the autograft (10.67 ± 1.03) and treatment groups (9.2 ± 1.30). Conclusions: Low-dose cyclosporine A/prednisone combination therapy does not influence bone viability and healing. A new orthotopic hemiface/calvaria allotransplantation model was established successfully that allows further studies on reconstruction of extensive craniomaxillofacial defects.

Development and in vivo validation of tissue-engineered, small-diameter vascular grafts from decellularized aortae of fetal pigs and canine vascular endothelial cells

BackgroundTissue engineering has emerged as a promising alternative for small-diameter vascular grafts. The aim of this study was to determine the feasibility of using decellularized aortae of fetal pigs (DAFPs) to construct tissue-engineered, small-diameter vascular grafts and to test the performance and application of DAFPs as vascular tissue-engineered scaffolds in the canine arterial system.MethodsDAFPs were prepared by continuous enzymatic digestion. Canine vascular endothelial cells (ECs) were seeded onto DAFPs in vitro and then the vascular grafts were cultured in a custom-designed vascular bioreactor system for 7xa0days of dynamic culture following 3xa0days of static culture. The grafts were then transplanted into the common carotid artery of the same seven dogs from which ECs had been derived (two grafts were prepared for each dog with one as a backup; therefore, a total of 14 tissue-engineered blood vessels were prepared). At 1, 3, and 6xa0months post-transplantation, ultrasonography and contrast-enhanced computed tomography (CT) were used to check the patency of the grafts. Additionally, vascular grafts were sampled for histological and electron microscopic examination.ResultsTissue-engineered, small-diameter vascular grafts can be successfully constructed using DAFPs and canine vascular ECs. Ultrasonographic and CT test results confirmed that implanted vascular grafts displayed good patency with no obvious thrombi. Six months after implantation, the grafts had been remodeled and exhibited a similar structure to normal arteries. Immunohistochemical staining showed that cells had evenly infiltrated the tunica media and were identified as muscular fibroblasts. Scanning electron microscopy showed that the graft possessed a complete cell layer, and the internal cells of the graft were confirmed to be ECs by transmission electron microscopy.ConclusionsTissue-engineered, small-diameter vascular grafts constructed using DAFPs and canine vascular ECs can be successfully transplanted to replace the canine common carotid artery. This investigation potentially paves the way for solving a problem of considerable clinical need, i.e., the requirement for small-diameter vascular grafts.

Utilizing Muscle-Derived Stem Cells to Enhance Long-Term Retention and Aesthetic Outcome of Autologous Fat Grafting: Pilot Study in Mice

Autologous fat grafting has been regarded as the ideal soft tissue filler for more than a century. Low long-term retention rate and unpredictability limit it from widespread clinical practice. Many theories for this have been proposed: lack of sufficient blood supply and subsequent necrosis is the most accepted. In this pilot study, we showed both macroscopically and microscopically the viability of muscle-derived stem cells (MDSCs) cotransplanted with fat placed intramuscularly for 3xa0months. MRI scanning showed a stronger fat signal in the MDSC-treated group than that of the control group. Moreover, histological evaluation exhibited well-preserved and intact fat cells in the MDSC-treated group. In contrast, the control group showed extensive fibrosis and fat graft loss. Furthermore, the MDSC-treated group possessed almost threefold greater capillary density than the control group. We conclude that cotransplantation of muscle-derived stem cells and autologous fat tissue improves the long-term survival of intramuscular fat transplants by promoting neovascularization.

The fetal porcine aorta and mesenteric acellular matrix as small-caliber tissue engineering vessels and microvasculature scaffold.

BackgroundThe extracellular matrix (ECM) is characterized by not only well-preserved scaffolds of organs and vascularized tissues, but also by extremely low immunogenicity during allo- or xeno-implantation. This study aimed to establish a model of a composite microvasculature network scaffold with a small-caliber-dominant vascular pedicle by decellularizing fetal porcine aorta and the conterminous mesentery.MethodsThe aorta and the conterminous mesenteric vascular system originating from the inferior mesenteric artery were harvested from fetal pigs at late gestation. All of the cellular components were removed by sequential treatment with Triton X-100 and sodium dodecyl sulfate. After the degree of decellularization was assessed, the fetal porcine aorta and mesenteric acellular matrix (FPAMAM) were transplanted into dogs.ResultsGross and histologic examination demonstrated the removal of cellular constituents with preservation of ECM architecture, including macrochannels and microchannels. The residual DNA content in the FPAMAM was less than 2xa0%. The aorta and microchannels were perfused well, and the fetal porcine aorta had good patency for more than 3xa0months.ConclusionsThe integrity of the FPAMAM provided a scaffold for the reconstruction of a rich vascular network with numerous segmentally radiating branches. Decellularized fetal porcine vascular tissue might be a potential alternative for xenogeneic transplantation based on its optimized properties and low immunogenicity.Level of Evidence IIThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Muscle derived stem cell contains the potential to enhance long term retention as well as an aesthetic outcome of autologous fat grafting

Autologous fat graft has been mentioned as a prospective source of soft-tissue filler for decades. It gives a natural consistency, is easy and safe to harvest, exhibits no hypersensitivity or foreign body reactions, and is readily available. However, the traditional fat grafting has its limitations in long term process, such as partial necrosis, loss of volume, and internal calcification. They all compromise the functional and aesthetic outcome of this procedure. In recent studies, the best results were obtained by transplanting fat tissue inside muscle, thus benefiting from its better blood supply. Muscle-derived stem cells have recently emerged as a promising source of multipotent cells which give rise to muscle fibers within muscular environment. Previous studies have also proved that muscle-derived stem cells are capable of releasing various kinds of angiogenesis agents, such as VEGF, HGF, and FGF. These cytokines are known to promote revascularization. Based on the foregoing facts, we postulate that co-transplant of autologous fat and muscle derived stem cells may enhance the long term retention and aesthetic outcome of fat grafting.

Expression profiles analysis of long non-coding RNAs identified novel lncRNA biomarkers with predictive value in outcome of cutaneous melanoma

Recent advancements in cancer biology have identified a large number of lncRNAs that are dysregulated expression in the development and tumorigenesis of cancers, highlighting the importance of lncRNAs as a key player for human cancers. However, the prognostic value of lncRNAs still remains unclear and needs to be further investigated. In the present study, we aim to assess the prognostic value of lncRNAs in cutaneous melanoma by integrated lncRNA expression profiles from TCGA database and matched clinical information from a large cohort of patients with cutaneous melanoma. We finally identified a set of six lncRNAs that are significantly associated with survival of patients with cutaneous melanoma. A linear combination of six lncRNAs (LINC01260, HCP5, PIGBOS1, RP11-247L20.4, CTA-292E10.6 and CTB-113P19.5) was constructed as a six-lncRNA signature which classified patients of training cohort into the high-risk group and low-risk group with significantly different survival time. The prognostic value of the six-lncRNA signature was validated in both the validation cohort and entire TCGA cohort. Moreover, the six-lncRNA signature is independent of known clinic-pathological factors by multivariate Cox regression analysis and demonstrated good performance for predicting three- and five-year overall survival by time-dependent receiver operating characteristic (ROC) analysis. Our study provides novel insights into the molecular heterogeneity of cutaneous melanoma and also shows potentially important implications of lncRNAs for prognosis and therapy for cutaneous melanoma.