Characterization of the Kinetics and Mechanism of Degradation of Human Mesenchymal Stem Cell-Laden Poly(ethylene glycol) Hydrogels.
Characterization of the Kinetics and Mechanism of Degradation of Human Mesenchymal Stem Cell-Laden Poly(ethylene glycol) Hydrogels.
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DOI：
10.1021/acsabm.8b00390
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发表时间：
2018-12
影响因子：
4.7
通讯作者：
M. Mazzeo;Tiffanie Chai;Maryam Daviran;Kelly M. Schultz
中科院分区：
文献类型：
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作者：
M. Mazzeo;Tiffanie Chai;Maryam Daviran;Kelly M. Schultz
人类间充质干细胞（hMSCs）是一种运动细胞，可以从它们的天然小生境迁移到伤口部位，在愈合过程中调节炎症。正在开发新材料作为hMSC递送平台以增强伤口愈合。为了作为有效的伤口愈合材料，水凝胶必须以与组织再生相同的速率降解，同时保持高细胞活力。这项工作确定了hMSC负载聚（乙二醇）（PEG）水凝胶中细胞介导的降解动力学和机制。我们使用了一种成熟的水凝胶支架，该支架由四臂星星PEG的骨架组成，该骨架用与基质金属蛋白酶（MMP）可降解肽交联的异戊烯官能化。该肽序列被细胞分泌的MMP切割，这使得hMSC在运动期间主动降解水凝胶。三种降解机制的特点：水解，非细胞酶和细胞介导的降解。我们使用本体流变学来表征水凝胶材料的性质，并在整个反应过程中量化降解。水解和非细胞的酶促降解首先在没有hMSC的水凝胶中表征，并且分别遵循一级动力学和Michaelis-Menten动力学。即使在流变仪上剪切后，在负载hMSC的水凝胶中也测量到高细胞活力。在确认hMSC活力后，本体流变学表征细胞介导的降解。当比较细胞介导的降解与非细胞降解机制时，细胞介导的降解以酶促降解为主。这表明具有hMSC的水凝胶主要由于细胞分泌的MMP而降解，并且由于水解而损失非常少的网络结构。模拟细胞介导的降解提供了由hMSC分泌的MMP的初始浓度的估计。通过改变hMSC的浓度，我们确定初始MMP浓度随着hMSC浓度的增加而增加。这项工作的特点支架降解的速率和机制，提供了新的见解，这些材料的设计作为植入式支架。
Human mesenchymal stem cells (hMSCs) are motile cells that migrate from their native niche to wounded sites where they regulate inflammation during healing. New materials are being developed as hMSC delivery platforms to enhance wound healing. To act as an effective wound healing material, the hydrogel must degrade at the same rate as tissue regeneration, while maintaining a high cell viability. This work determines the kinetics and mechanism of cell-mediated degradation in hMSC-laden poly(ethylene glycol) (PEG) hydrogels. We use a well-established hydrogel scaffold that is composed of a backbone of four-arm star PEG functionalized with norbornene that is cross-linked with a matrix metalloproteinase (MMP) degradable peptide. This peptide sequence is cleaved by cell-secreted MMPs, which allow hMSCs to actively degrade the hydrogel during motility. Three mechanisms of degradation are characterized: hydrolytic, noncellular enzymatic and cell-mediated degradation. We use bulk rheology to characterize hydrogel material properties and quantify degradation throughout the entire reaction. Hydrolysis and noncellular enzymatic degradation are first characterized in hydrogels without hMSCs, and follow first-order and Michaelis-Menten kinetics, respectively. A high cell viability is measured in hMSC-laden hydrogels, even after shearing on the rheometer. After confirming hMSC viability, bulk rheology characterizes cell-mediated degradation. When comparing cell-mediated degradation to noncellular degradation mechanisms, cell-mediated degradation is dominated by enzymatic degradation. This indicates hydrogels with hMSCs are degraded primarily due to cell-secreted MMPs and very little network structure is lost due to hydrolysis. Modeling cell-mediated degradation provides an estimate of the initial concentration of MMPs secreted by hMSCs. By changing the concentration of hMSCs, we determine the initial MMP concentration increases with increasing hMSC concentration. This work characterizes the rate and mechanism of scaffold degradation, giving new insight into the design of these materials as implantable scaffolds.