Obradovic B, Carrier R L, Vunjak-Novakovic G, Freed L E
Division of Health Sciences and Technology, Massachusetts Institute of Technology, E25-342, Cambridge, Massachusetts 02139, USA.
Biotechnol Bioeng. 1999 Apr 20;63(2):197-205. doi: 10.1002/(sici)1097-0290(19990420)63:2<197::aid-bit8>3.0.co;2-2.
Tissue engineered cartilage can be grown in vitro if the necessary physical and biochemical factors are present in the tissue culture environment. Cell metabolism and tissue composition were studied for engineered cartilage cultured for 5 weeks using bovine articular chondrocytes, polymer scaffolds (5 mm diameter x 2 mm thick fibrous discs), and rotating bioreactors. Medium pH and concentrations of oxygen, carbon dioxide, glucose, lactate, ammonia, and glycosoaminoglycan (GAG) were varied by altering the exchange rates of gas and medium in the bioreactors. Cell-polymer constructs were assessed with respect to histomorphology, biochemical composition and metabolic activity. Low oxygen tension ( approximately 40 mmHg) and low pH ( approximately 6.7) were associated with anaerobic cell metabolism (yield of lactate on glucose, YL/G, of 2.2 mol/mol) while higher oxygen tension ( approximately 80 mmHg) and higher pH ( approximately 7.0) were associated with more aerobic cell metabolism (YL/G of 1.65-1.79 mol/mol). Under conditions of infrequent medium replacement (50% once per week), cells utilized more economical pathways such that glucose consumption and lactate production both decreased, cell metabolism remained relatively aerobic (YL/G of 1.67 mol/mol) and the resulting constructs were cartilaginous. More aerobic conditions generally resulted in larger constructs containing higher amounts of cartilaginous tissue components, while anaerobic conditions suppressed chondrogenesis in 3D tissue constructs.
如果组织培养环境中存在必要的物理和生化因素，就可以在体外培养组织工程软骨。使用牛关节软骨细胞、聚合物支架（直径5毫米×厚2毫米的纤维盘）和旋转生物反应器，对培养5周的工程软骨的细胞代谢和组织组成进行了研究。通过改变生物反应器中气体和培养基的交换速率，来改变培养基的pH值以及氧气、二氧化碳、葡萄糖、乳酸、氨和糖胺聚糖（GAG）的浓度。从组织形态学、生化组成和代谢活性方面对细胞-聚合物构建体进行评估。低氧张力（约40 mmHg）和低pH值（约6.7）与无氧细胞代谢相关（葡萄糖产生乳酸的产率，YL/G，为2.2 mol/mol），而较高的氧张力（约80 mmHg）和较高的pH值（约7.0）与更多的有氧细胞代谢相关（YL/G为1.65 - 1.79 mol/mol）。在不频繁更换培养基（每周一次更换50%）的条件下，细胞利用更经济的途径，使得葡萄糖消耗和乳酸产生均减少，细胞代谢保持相对有氧（YL/G为1.67 mol/mol），并且最终构建体呈软骨状。更多的有氧条件通常会导致构建体更大，含有更高量的软骨组织成分，而无氧条件会抑制三维组织构建体中的软骨形成。
