Water-insoluble fragmin/protamine microparticles of about 0.5-1 mum in diameter were prepared by simple mixing of low-molecular-weight heparin (fragmin) with protamine. We investigated the capability of these microparticles to immobilize fibroblast growth factor (FGF)-2, to protect FGF-2 against degradation, to enhance FGF-2 activity, and to facilitate controlled release of FGF-2. FGF-2 bound to the fragmin/protamine microparticles with high affinity (Kd = 2.08 x 10(-9) M) and the half-life of FGF-2-activity was prolonged substantially through binding of FGF-2 to the microparticles, by protection of FGF-2 from inactivation by heat and proteolysis. After subcutaneous injection into the back of mice, the fragmin/protamine microparticles underwent biodegradation and disappeared in about 2 weeks. A similar injection of FGF-2-containing microparticles resulted in significant neovascularization and fibrous tissue formation near the injection site after 1 week. These results indicate that controlled release of biologically active FGF-2 occurs through both slow diffusion and biodegradation of the microparticles, with subsequent induction of neovascularization. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009.

Adipose tissue-derived stromal cells (ATSCs) have recently gained widespread attention as a potential alternate source to bone marrow-derived mesenchymal stem cells with a proliferative capacity and a similar ability to undergo multilineage differentiation. In this study, we evaluated the effectiveness of freshly isolated autologous ATSCs-containing atelocollagen matrix with silicon membrane (ACMS) on wound healing of diabetic (db/db) mice. Cultured ATSCs from (db/db) mice secreted significant amounts of growth factors and cytokines, which are suitable for wound repair. Two full thickness round skin defects were made on the backs of healing-impaired db/db mice. Freshly isolated autologous ATSCs-containing ACMS or ACMS alone were applied to the wounds. Twelve mice were treated and then killed at 1 or 2 weeks (n = 6 each). Histologic sections of the wounds were prepared at each time period after treatment. Histologic examination demonstrated significantly advanced granulation tissue formation, capillary formation, and epithelialization in diabetic healing-impaired wounds treated with autologous ATSCs-containing ACMS, compared with mice treated with ACMS alone. These results suggested that transplantation of autologous ATSCs-containing ACMS significantly accelerated wound healing in diabetic healing-impaired db/db mice.

We produced a chitosan/fucoidan micro complex-hydrogel as a carrier for controlled release of heparin binding growth factors such as fibroblast growth factor (FGF)-2. Material consisting of a soluble chitosan (CH-LA) mixed with fucoidan yielded a water-insoluble and injectable hydrogel with filamentous particles. In this study, we examined the ability of the chitosan/fucoidan complex-hydrogel to immobilize FGF-2 and to protect its activity, as well as the controlled release of FGF-2 molecules. The chitosan/fucoidan complex-hydrogel has high affinity for FGF-2 (K(d) = 5.4 x 10(-) (9)M). The interaction of FGF-2 with chitosan/fucoidan complex-hydrogel substantially prolonged the biological half-life time of FGF-2. It also protected FGF-2 from inactivation, for example by heat and proteolysis, and enhance FGF-2 activity. When FGF-2-containing complex-hydrogel was subcutaneously injected into the back of mice, significant neovascularization and fibrous tissue formation were induced near the site of injection at 1 week, and the complex-hydrogel was biodegraded and disappeared by 4 weeks. These findings indicate that controlled release of biologically active FGF-2 molecules is caused by both slow diffusion and biodegradation of the complex-hydrogel, and that subsequent induction of vascularization occurs. FGF-2-containing chitosan/fucoidan micro complex-hydrogel is thus useful and convenient for treatment of ischemic disease.

An aqueous solution of photocrosslinkable chitosan containing azide groups and lactose moieties (Az-CH-LA) incorporating paclitaxel formed an insoluble hydrogel within 30 s of ultraviolet light (UV) irradiation. The chitosan hydrogel showed strong potential for use as a new tissue adhesive in surgical applications and wound dressing. The fibroblast growth factor (FGF)-2 molecules retained in the chitosan hydrogel and in an injectable chitosan/IO(4)-heparin hydrogel remain biologically active, and were gradually released from the hydrogels as they biodegraded in vivo. The controlled release of biologically active FGF-2 molecules from the hydrogels caused induction of angiogenesis and collateral circulation occurred in healing-impaired diabetic (db/db) mice and in the ischemic limbs of rats. Paclitaxel, which is an antitumor reagent, was also retained in the chitosan hydrogel and remained biologically active as it was released on degradation of the hydrogel in vivo. The chitosan hydrogels incorporating paclitaxel effectively inhibited tumor growth and angiogenesis in mice. The purpose of this review is to describe the effectiveness of chitosan hydrogel as a local drug delivery carrier for agents (e.g., FGF-2 and paclitaxel) to control angiogenesis. It is thus proposed that chitosan hydrogel may be a promising new local carrier for drugs such as FGF-2 and paclitaxel to control vascularization.

The aim of this study was to evaluate the potential accelerating effects of an adipose tissue-derived stromal cells (ATSC)-containing atelocollagen matrix with silicone membrane (ACMS) for repairing mitomycin C-treated healing-impaired wounds. Mitomycin C was applied to full-thickness skin incisions in this study to create a healing-impaired wound model in rat. After thoroughly washing out the mitomycin C from the wound, ACMS alone or ATSC-containing ACMS was applied to the wounds. Histological sections of the wounds were then prepared at indicated time periods after the treatments. These results indicated significantly advanced granulation tissue and capillary formations in the healing-impaired wounds treated with ATSC-containing ACMS compared with those treated with ACMS alone. Thus, this study suggested that transplantation of inbred ATSC-containing ACMS is effective for repairing healing-impaired wounds.