Development of polyvinyl alcohol-collagen composite and its biocompatibility as tissue substitute / 中国组织工程研究

ABSTRACT

BACKGROUND: Polyvinyl alcohol (PVA) displays limitation to cell adsorbability. Can collagen improve the adsorbability of PVA to cells?OBJECTIVE: To develop a novel type composite of PVA and collagen, and explore the feasibility to serve as soft tissue substitute.DESIGN: Single sample observation.SETTING: Guangzhou Red Cross Hospital, Jinan University Medical College, Guangzhou Institute of Traumatic Surgery.MATERIALS Fifteen New Zealand rabbits of 2.0-3.0 kg, either male or female, were provided by Medical Experimental Animal Center of Guangdong Province. The experiment was carried out in the Laboratory of Guangzhou Institute of Traumatic Surgery, and the experimental procedure was accorded with the animal ethical standards. Bovine typeI collagen was purchased from Guangzhou Trauer Biotechnology Co., Ltd. and PVA-124 from Guangzhou Chemical Reagent and Instrumentation Co., Ltd.METHODS: The experiment was performed in Guangzhou Red Cross Hospital, Jinan University Medical College between July 2003 and December 2006. ①Preparation of PVA-collagen material: 5 g/L bovine type I collagen was mixed with 5% PVA-124 at a ratio of 1 1. The mixture was freeze-dried at vacuum until becoming gelatinous. The internal structure was observed under the use of scanning electron microscope. ②Cytotoxicity test PVA-collagen composite was cut into pieces of 10 mm×5 mm× 1 mm, put into 48-well culture plate after sterilized by Y ray, cultured with 1×104 3T3 cells in each well. Cell growth was observed under scanning electron microscope and laser scanning confocal microscope. ③Embedding test in vivo Two longitudinal incisions were cut at the two sides of spine. The subcutaneous tissue was separated bluntly to form subcutaneous lacuna. Four pieces of PVA-collagen material were implanted in the lacuna and fixed. Nine specimens and the surrounding tissues were harvested from three rabbits each at one, four, eight and sixteen weeks postoperatively for pathological observation.MAIN OUTCOME MEASURES: The internal structure of gel film under scanning electron microscope, cytotoxicity test and embedding test in vivo results.RESULTS: ①Internal structure of PVA-collagen material:PVA-collagen material showed white gel shape after freeze-drying at vacuum. Penetrating three-dimensional pores were observed in the surface and inner section under scanning electron microscope. ②Cytotoxicity test results showed that 3T3 cells grew normally on the PVA-collagen material. ? Embedding test in vivo results suggested that one week after PVA-collagen implantation, foreign body reaction occurred, and the interface between material and tissue was clear. Four weeks later, only rare lymphocyte infiltration was observed, and a great amount of fibroblast hyperplasia formed collagen fibrils and false simple cuboidal epithelium coating material. In 8 weeks, no lymphocyte infiltration, neutrophilic granulocyte infiltration or foreign body giant cell were found; dense capsule wall and capsule coating material generated from a great amount of fibroblasts were observed. In 16 weeks, extending collagen fibrils were found arranged regularly with shrank nucleus, showing long ovoid or long fusiform in shape; no new formation small vessels, lymphocyte, neutrophilic granulocyte infiltration or foreign body giant cell infiltration were observed. The capsule wall was stable and thinned. CONCLUSION: PVA-collagen composite has good cell compatibility and tissue compatibility but no toxic or adverse effect. It can serve as in vivo implant.