Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA.
Case Center for Multimodal Evaluation of Engineered Cartilage, Case Western Reserve University, Cleveland, OH, 44106, USA.
Ann Biomed Eng. 2018 Nov;46(11):1896-1910. doi: 10.1007/s10439-018-2067-x. Epub 2018 Jun 14.
Chondrogenesis of human mesenchymal stem cells (hMSCs) is an important biological process in many applications including cartilage tissue engineering. We investigated the glucose uptake characteristics of aggregates of hMSCs undergoing chondrogenesis over a 3-week period both experimentally and by using a mathematical model. Initial concentrations of glucose in the medium were varied from 1 to 4.5 g/L to mimic limiting conditions and glucose uptake profiles were obtained. A reaction-diffusion mathematical model was implemented and solved to estimate kinetic parameters. Experimental glucose uptake rates increased with culture time for aggregates treated with higher initial glucose concentrations (3 and 4.5 g/L), whereas they decreased or remained constant for those treated with lower initial glucose concentrations (1 and 2 g/L). Lactate production rate increased by as much as 40% for aggregates treated with higher initial glucose concentrations (2, 3 and 4.5 g/L), whereas it remained constant for those treated with 1 g/L initial glucose concentration. The estimated DNA-normalized maximum glucose uptake rate decreased by a factor of 9 from day 0-2 (12.5 mmol/s/g DNA) to day 6-8 (1.5 mmol/s/g DNA), after which it started to increase. On day 18-20, its value (17.5 mmol/s/g DNA) was about 11 times greater than its lowest value. Further, the extracellular matrix levels of aggregates at day 14 and day 21 correlated with their overall glucose uptake and lactate production. The results suggest that during chondrogenesis, for optimal results, cells require increasing amounts of glucose. Our results also suggest that diffusion limitations play an important role in glucose uptake even in the smaller size aggregate model of chondrogenesis. Further, the results indicate that glucose uptake or lactate production can be a tool for predicting the end quality of tissue during the process of chondrogenesis. The estimated kinetic parameters can be used to model glucose requirements in cartilage tissue engineering applications.
人骨髓间充质干细胞（hMSCs）的软骨分化是许多应用中的一个重要生物学过程，包括软骨组织工程。我们通过实验和数学模型研究了 3 周内软骨分化过程中 hMSC 聚集物的葡萄糖摄取特性。实验中，培养基中葡萄糖的初始浓度从 1 到 4.5 g/L 变化，以模拟限制条件，并获得葡萄糖摄取曲线。实施并求解了一个反应扩散数学模型，以估计动力学参数。对于用较高初始葡萄糖浓度（3 和 4.5 g/L）处理的聚集物，实验葡萄糖摄取率随培养时间的增加而增加，而对于用较低初始葡萄糖浓度（1 和 2 g/L）处理的聚集物，其葡萄糖摄取率则降低或保持不变。对于用较高初始葡萄糖浓度（2、3 和 4.5 g/L）处理的聚集物，乳酸生成率增加了高达 40%，而对于用 1 g/L 初始葡萄糖浓度处理的聚集物，其乳酸生成率则保持不变。估计的 DNA 归一化最大葡萄糖摄取率从第 0-2 天（12.5 mmol/s/g DNA）降低到第 6-8 天（1.5 mmol/s/g DNA），降低了 9 倍，之后开始增加。在第 18-20 天，其值（17.5 mmol/s/g DNA）比最低值高约 11 倍。此外，第 14 天和第 21 天聚集物的细胞外基质水平与其总葡萄糖摄取和乳酸生成相关。结果表明，在软骨分化过程中，为了获得最佳效果，细胞需要更多的葡萄糖。我们的结果还表明，即使在较小的软骨分化聚集物模型中，扩散限制也在葡萄糖摄取中起重要作用。此外，结果表明，葡萄糖摄取或乳酸生成可以作为预测软骨分化过程中组织最终质量的工具。估计的动力学参数可用于软骨组织工程应用中葡萄糖需求的建模。
