Po-Hong Lai

A genipin-crosslinked gelatin membrane as wound-dressing material: in vitro and in vivo studies

A naturally occurring crosslinking agent (genipin) was used in this study to crosslink gelatin hydrogel to develop a wound-dressing membrane. The study was to investigate the in vitro characteristics of the genipin-crosslinked gelatin membrane. The glutaraldehyde-crosslinked counterpart, at a similar crosslinking degree, was used as control. Additionally, an in vivo experiment was undertaken to study the wound healings covered with the glutaraldehyde- and genipin-crosslinked dressings in a rat model. The in vitro results obtained suggested that crosslinking of gelatin membranes with glutaraldehyde or genipin may produce distinct crosslinking structures. The differences in crosslinking structure can significantly affect the mechanical property, water-vapor-transmission rate, swelling ratio, degradation against enzyme and cellular compatibility of the crosslinked membranes. In the in vivo study, it was found that the degree of inflammatory reaction for the wound treated with the genipin-crosslinked dressing was significantly less severe than that covered with the glutaraldehyde-crosslinked dressing throughout the entire course of the study. Additionally, the healing rate for the wound treated with the genipin-crosslinked dressing was notably faster than its glutaraldehyde-crosslinked counterpart.

A Natural Compound (Ginsenoside Re) Isolated from Panax ginseng as a Novel Angiogenic Agent for Tissue Regeneration

No HeadingPurpose.The primary challenge for tissue engineering is to develop a vascular supply that can support the metabolic needs of the engineered tissues in an extracellular matrix. In this study, the feasibility of using a natural compound, ginsenoside Re, isolated from Panax ginseng in stimulating angiogenesis and for tissue regeneration was evaluated.Methods.Effects of ginsenoside Re on the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) were examined in vitro. Additionally, angiogenesis and tissue regeneration in a genipin-fixed porous acellular bovine pericardium (extracellular matrix; ECM) incorporated with ginsenoside Re implanted subcutaneously in a rat model were investigated. Basic fibroblast growth factor (bFGF) was used as a control.Results.It was found that HUVEC proliferation, migration in a Transwell plate, and tube formation on Matrigel were all significantly enhanced in the presence of bFGF or ginsenoside Re. Additionally, effects of ginsenoside Re on HUVEC proliferation, migration, and tube formation were dose-dependent and reached a maximal level at a concentration of about 30 μg/ml. The in vivo results obtained at 1 week postoperatively showed that the density of neocapillaries and the tissue hemoglobin content in the ECMs were significantly enhanced by bFGF or ginsenoside Re. These results indicated that angiogenesis in the ECMs was significantly enhanced by loading with bFGF or ginsenoside Re. At 1 month postoperatively, vascularzied neo-connective-tissue fibrils were found to fill the pores in the ECMs loaded with bFGF or ginsenoside Re.Conclusions.The aforementioned results indicated that like bFGF, ginsenoside Re-associated induction of angiogenesis enhanced tissue regeneration, supporting the concept of therapeutic angiogenesis in tissue-engineering strategies.

A naturally occurring crosslinking agent extracted from gardenia fruit and its applications in tissue engineering

A naturally occurring crosslinking agent, genipin, was extracted by our group from the fruit of Gardenia jasminoides ELLIS, an herbal medicine. It was shown that genipin is an effective crosslinking agent and is significantly less cytotoxic than glutaraldehyde. It was also found in several animal studies that the inflammatory reaction to genipin-fixed tissue was significantly lower than its glutaraldehyde-fixed counterpart. It was reported that cell extraction may decrease the antigenic loads within biological tissues. A cell extraction process was recently used by our group to remove the cellular components from bovine pericardia, leaving a framework of largely insoluble collagen, elastin, and tightly bound glycosaminoglycans. It was found that acellular tissues can provide a natural microenvironment for host cell migration and may be used as an extracellular matrix to accelerate tissue regeneration. Tissue regeneration rate for the genipin-fixed acellular tissue was significantly faster than its glutaraldehyde-fixed counterpart. The aforementioned acellular tissues fixed with genipin are currently used as tissue-engineering scaffolds for the development of a new biological patch, vascular graft, heart valve prosthesis,anti-adhesion membrane, and myocardial tissue applications.