Role of Hedgehog Signaling Pathways in Multipotent Mesenchymal Stem Cells Differentiation.

Multipotent mesenchymal stem cells (MSCs) have high self-renewal and multi-lineage differentiation potentials and low immunogenicity, so they have attracted much attention in the field of regenerative medicine and have a promising clinical application. MSCs originate from the mesoderm and can differentiate not only into osteoblasts, cartilage, adipocytes, and muscle cells but also into ectodermal and endodermal cell lineages across embryonic layers. To design cell therapy for replacement of damaged tissues, it is essential to understand the signaling pathways, which have a major impact on MSC differentiation, as this will help to integrate the signaling inputs to initiate a specific lineage. Hedgehog (Hh) signaling plays a vital role in the development of various tissues and organs in the embryo. As a morphogen, Hh not only regulates the survival and proliferation of tissue progenitor and stem populations but also is a critical moderator of MSC differentiation, involving tri-lineage and across embryonic layer differentiation of MSCs. This review summarizes the role of Hh signaling pathway in the differentiation of MSCs to mesodermal, endodermal, and ectodermal cells.

Endothelial-mesenchymal transition as a novel mechanism for generating myofibroblasts during wound healing and scarring.

BACKGROUND: The endothelial-mesenchymal transition (EndMT) is an important mechanism in tissue regeneration and the development of organ fibrosis. Whether EndMT occurs in wound healing and scarring remains unknown. MATERIALS AND METHODS: The isolated cells from the normal dermal tissue and the wound tissue of mouse with full-thickness skin wound, and human scar tissue sections were performed with CD31/factorVII and α-SMA immunohistochemical staining and H and E staining. The ratio of factor VII or CD31/α-SMA double-positive cells in factor VII-positive cells was assessed in the isolated cells and in scar tissues. RESULTS: In this study, we found that approximately 27-60% of ECs coexpressed VII factor and α-SMA in the isolated cells from the wound tissues of mice, which was significantly higher than that of normal dermal tissue cells. Accordingly, the number of CD31/α-SMA double-positive cells in mouse wound tissue sections was also significantly more than that in normal dermal tissue sections. In scar tissues, in addition to high-density microvessels, a large number of proliferative ECs in scar strama and CD31/α-SMA double-positive cells were also found. Approximately 46.82 to 84.11% of ECs and 68.77 to 95.25% of myofibroblasts coexpressed VII factor and α-SMA, and these two values in hypertrophic scars were significantly higher than those in keloids. CONCLUSION: These results confirmed that ECs might contribute to the emergence of myofibroblasts in the wound and scar tissue via the process of EndMT.

Optimal H2O2 preconditioning to improve bone marrow mesenchymal stem cells' engraftment in wound healing.

BACKGROUND: The transplantation of bone marrow mesenchymal stem cells (BMSCs) is a promising therapeutic strategy for wound healing. However, the poor migration capacity and low survival rate of transplanted BMSCs in wounds weaken their potential application. OBJECTIVE: To identify the optimal protocol for BMSCs preconditioned with H2O2 and improve the therapeutic efficacy using H2O2-preconditioned BMSCs in wound healing. METHODS: Mouse BMSCs were exposed to various concentrations of H2O2, and the key cellular functional properties were assessed to determine the optimal precondition with H2O2. The H2O2-preconditioned BMSCs were transplanted into mice with full-thickness excisional wounds to evaluate their healing capacity and tissue engraftment. RESULTS: Treatment BMSCs with 50 µM H2O2 for 12 h could significantly enhance their proliferation, migration, and survival by maximizing the upregulation of cyclin D1, SDF-1, and its receptors CXCR4/7 expressions, and activating the PI3K/Akt/mTOR pathway, but inhibiting the expression of p16 and GSK-3ß. Meanwhile, oxidative stress-induced BMSC apoptosis was also significantly attenuated by the same protocol pretreatment with a decreased ratio of Bax/Bcl-2 and cleaved caspase-9/3 expression. Moreover, after the identification of the optimal protocol of H2O2 precondition in vitro, the migration and tissue engraftment of transfused BMSCs with H2O2 preconditioning were dramatically increased into the wound site as compared to the un-preconditioned BMSCs. The increased microvessel density and the speedy closure of the wounds were observed after the transfusion of H2O2-preconditioned BMSCs. CONCLUSIONS: The findings suggested that 50 µM H2O2 pretreated for 12 h is the optimal precondition for the transplantation of BMSCs, which gives a considerable insight that this protocol may be served as a promising candidate for improving the therapeutic potential of BMSCs for wound healing.

Biomimetic collagen biomaterial induces in situ lung regeneration by forming functional alveolar.

In situ restoration of severely damaged lung remains difficult due to its limited regeneration capacity after injury. Artificial lung scaffolds are emerging as potential substitutes, but it is still a challenge to reconstruct lung regeneration microenvironment in scaffold after lung resection injury. Here, a 3D biomimetic porous collagen scaffold with similar structure characteristics as lung is fabricated, and a novel collagen binding hepatocyte growth factor (CBD-HGF) is tethered on the collagen scaffold for maintaining the biomimetic function of HGF to improve the lung regeneration microenvironment. The biomimetic scaffold was implanted into the operative region of a rat partial lung resection model. The results revealed that vascular endothelial cells and endogenous alveolar stem cells entered the scaffold at the early stage of regeneration. At the later stage, inflammation and fibrosis were attenuated, the microvascular and functional alveolar-like structures were formed, and the general morphology of the injured lung was restored. Taken together, the functional 3D biomimetic collagen scaffold facilitates recovery of the injured lung, alveolar regeneration, and angiogenesis after acute lung injury. Particularly, this is the first study of lung regeneration in vivo guided by biomimetic collagen scaffold materials, which supports the concept that tissue engineering is an effective strategy for alveolar regeneration.

Lung endothelial cell-targeted peptide-guided bFGF promotes the regeneration after radiation induced lung injury.

Basic fibroblast growth factor (bFGF) can protect the lung against radiation-induced pulmonary vascular endothelial apoptosis and subsequent radiation-induced lung injury (RILI). However, guiding bFGF to pulmonary vascular endothelial cells is a key determinant for the success of bFGF therapy. To improve the lung-targeting ability of bFGF, a lung endothelial cell-targeting peptide was fused to bFGF (LET-bFGF). An in vitro biological activity assay indicated that fusion of LET did not affect the bioactivity of bFGF. In addition, the fused protein showed superior lung-targeting ability following intravenous injection. Upon injecting LET-bFGF intravenously after thorax radiation, LET-bFGF could better protect against pulmonary vascular endothelial cell apoptosis as early as 4 h post-radiation. Compared with native bFGF, enhanced therapeutic effects of LET-bFGF were also observed in terms of decreased vascular abnormalities, disorganized lung structure, inflammatory cell migration, and lung density at 2 months post-radiation. Therefore, lung endothelial cell-targeted bFGF may represent a promising remedy for RILI.

Transdermal Vascular Endothelial Growth Factor Delivery with Surface Engineered Gold Nanoparticles.

Skin injuries caused by burns or radiation remain a serious concern in terms of clinical therapy. Because of the damage to the epidermis or dermis, angiogenesis is needed to repair the skin. Vascular endothelial growth factor (VEGF) is one of the most effective factors for promoting angiogenesis and preventing injury progression, but the delivery of VEGF to lesion sites is limited by the skin barrier. Recently, gold nanoparticle (AuNP)-mediated drug delivery into or through the epidermis and dermis has attracted much attention. However, the efficacy of the AuNP-mediated transdermal drug delivery remains unknown. In this study, gold nanoparticles were conjugated with VEGF and generated a surface by carrying negative charges, showing an ideal transdermal delivery efficacy for VEGF in wound repair. Our findings may provide new avenues for the treatment of cutaneous injuries.