Cellular compatibility of poly (lactic-co-glycolic acid)scaffold / 中国组织工程研究

ABSTRACT

BACKGROUND:The poly-lactic acid and its ramifications have many advantages, such as eligible biocompatibility,nontoxicity of degradation product, easy procession and suitable intensity. Thus, they have been widely used in bone tissue engineering.OBJECTIVE: To study the cellular biocompatibility and in vitro adhesion of poly(lactic-co-glycolic acid) (PLGA) scaffold and bone marrow stromal stem cells (BMSCs) so as to provide a basis for preparation a PLGA scaffold that can load many cytokines.DESIGN: Contrast observation.SETTING: Department of Orthopaedics and Traumatology in Nanfang Hospital of Southern Medical University.MATERIALS The experiment was carried out in Key Laboratory of Tissue Construction and Detection of Guangdong Province from September 2004 to June 2005. One New Zealand healthy male rabbit (2 months old, 1.5-2.0 kg weight)was adopted in this study. Experimental materials PLGA scaffold was obtained from Institute of Polymer Science in Sun Yat-sen University); beta-tricalcium phosphate (β-TCP) was supplied by AO Company (Switzerland).METHODS: Bone marrow was aspirated from the New Zealand rabbit. Mononuclear cells were harvested using whole bone marrow culturing, then were induced and amplified in the conditional culture medium. BMSCs were inoculated onto the PLGA and β-TCP at a concentration of 1 ×109 L-1, while those in the medium without materials were taken as blank control group. The development of implanted cells and the adhesion between cells and materials were observed with phase contrast microscope and scanning electron microscope. The proliferation and cycle of cells were tested with MTT method and flow cytometry.MATN OUTCOME MEASURES: ①Phase contrast microscope was used to observe the development of cells and the adherence between cells and materials at a fixed time every day. ②Cellular development on days 1, 3, 6 was observed by scanning electron microscope. ③Cellular proliferation was detected by MTT method. ④Alkaline phosphatase (ALP) activity was determined by chemical colorimetry.⑤Flow cytometer test The effects of PLGA and β-TCP on the cellular cycle, content of DNA and polyploid levels of BMSCs were investigated. The DNA index of the candidate cells was also calculated.RESULTS: ①Phase contrast microscope observation In the blank control group, cells culture for 7-10 days presented a larger number of shuttle-shaped, and no contact inhibition effect was observed. The time of cells beginning adherence in PLGA group was obviously later than that in β-TCP group. Cells began to develop on the circumambience and surface of the materials, with the prolonging of culture time. Most of the cells were multangular. The cells in both PLGA and β-TCP groups were similar to those in control group in items of cellular development and shape. ②Scanning electron microscope observation On the seventh day of culture, the cells of control group remained a monolayer and amalgamated to be a patch with multangular-shaped ones increasing. There were substances in granule shape on the surface of the cells and micro-silk links between cells. In PLGA group, the cells After 7 days' cultivation proliferated sharply, and the compressed-shaped ones were inosculated to be a patch through integrations among cells, resulting in a large number of matrixes. While in β-TCP group, the number of cells increased from the 7th day. The cells were combined together to be a monolayer and moved to pores with matrixes creating out of cells.③Cellular proliferation The number of the cells in each group all increased to some extents. However, there was no significant difference between the PLGA group and the control group, as well as the PLGA group and the β-TCP group (P ＞ 0.05).④ALP activity The　content of ALP in all the groups enhanced without exception, while the activities between the PLGA group and the Both control group, as well as the PLGA group and the β-TCP group had no significant difference (P ＞ 0.05).⑤Cellular cycleBoth PLGA and β-TCP had slight effects on cellular cycle of BMSCs. The cells in each group were all normal diploid,and no heteroploid cells were discovered.CONCLUSION: This type of PLGA scaffold possesses good cellular biocompatibility, and can be used as a carrier of many factors in bone tissue engineering.