In vivo biodegradability of the composite materials for tracheal prosthesis in rats: Collagen/hydroxyapatite and poly(lactic-co-glycolic acid)

Hongcan SHI; Zhifei XU; Xiong QIN

ABSTRACT

BACKGROUND:

Preparing the tracheal prosthesis by biomaterials is crucial for studying the implant of long tracheal defect.The biocompatibility and biodegradability of collagen/hydroxyapatite (Col/HAp) and poly(lactic-co-glycolic acid) (PLGA) in vivo, as a artificial material for tracheal prosthesis, need to be observed.

OBJECTIVE:

To explore in vivo biodegradability of Col/HAp and PLGA of tracheal prosthesis in rats.

DESIGN:

Randomized controlling observation.

SETTING:

Department of Thoracic and Cardiovascular Surgery, Clinical College of Yangzhou University; Department of Thoracic and Cardiovascular Surgery, Changzheng Hospital of the Second Military Medical University of Chinese PLA.MATERIALS The experiment was carried out in the National Experimental Animal Center of the Second Military Medical University of Chinese PLA from March 2003 to December 2004. Sixteen SD rats of either gender were offered by this center, aged three months and weighed 150-170 g. Col/HAp and PLGA (the copolymer of polylactic acid and polyglycolic acid according to the percent of 9010) were self-made.

METHODS:

①Empirical process Rats were fed adaptively for 1 week and anesthetized. Then undermining dissection was performed along with musculi dorsal surface toward spine bilaterally, so as to form two capsular gaps, which were implanted with Col/HAp sponge and PLGA fiber mesh cloth respectively, in a size of 10 mm ×10 mm. ②Empirical evaluation The postoperative activity, incision healing and rejection of rats were observed; 2, 4, 6, 8 weeks postoperatively, the Col/HAp sponge and PLGA mat that were embedded subcutaneously as well as surrounding tissues were determined using scanning electron microscope or transmission electron microscope.MAIN OUTCOME

MEASURES:

In vivo biodegradability of two materials implanted in rats at different time points.

RESULTS:

①All the animals could carry out normal activity, respiration and diet; no incision infection, fluidity, necrosis or sinus tract appeared; there was no edema in the skins of implanted area, neither hypersensitiveness nor toxicity was found; the implant materials had no rejection. ②The features of the implanted materials varied throughout the implantation. During the follow-up, the infiltration of inflammatory cells was found in the interface between the implants and neighboring host tissues in the early stage, phagocytes and fibroblastic cells were also observed later. As the process went on, the materials were biodegraded gradually, encapsulated by phagocytes, and replaced by newly generated fibrous tissues. No remarkable harmful influences of the composite materials on the neighboring host tissues such as apomorphosis, necrosis, hyperplasia and foreign body reaction were observed grossly and microscopically.

CONCLUSION:

All the implants show a good biocompatibility and biodegradability. Both Col/HAp and PLGA go through a gradual process of biodegradability, biological absorption and replacement by host tissues ultimately in vivo, which suggest that these two kinds of composite biomaterials will be used safely in developing tracheal prosthesis.