Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.
Department of Pathology, John Cochran VA Medical Center, St. Louis, MO, USA.
FASEB J. 2020 Sep;34(9):12976-12990. doi: 10.1096/fj.202001274R. Epub 2020 Aug 9.
Fibrosis is driven by a misdirected cell response causing the overproduction of extracellular matrix and tissue dysfunction. Numerous pharmacological strategies have attempted to prevent fibrosis but have attained limited efficacy with some detrimental side effects. While stem cell treatments have provided more encouraging results, they have exhibited high variability and have not always improved tissue function. To enhance stem cell efficacy, we evaluated whether mechanical memory could direct cell response. We hypothesized that mechanically pre-conditioning on a soft matrix (soft priming) will delay adipose-derived stem cell (ASC) transition to a pro-fibrotic phenotype, expanding their regenerative potential, and improving healing in a complex tissue environment. Primary ASCs isolated from rat and human subcutaneous fat exhibited mechanical memory, demonstrated by a delayed cell response to stiffness following two weeks of soft priming including decreased cell area, actin coherency, and extracellular matrix production compared to cells on stiff substrates. Soft primed ASCs injected into our rat model of post-traumatic elbow contracture decreased histological evidence of anterior capsule fibrosis and increased elbow range-of-motion when evaluated by joint mechanics. These findings suggest that exploiting mechanical memory by strategically controlling the culture environment during cell expansion may improve the efficacy of stem cell-based therapies targeting fibrosis.
纤维化是由细胞反应失调引起的，导致细胞外基质过度产生和组织功能障碍。许多药物策略试图预防纤维化，但效果有限，且存在一些不良副作用。虽然干细胞治疗提供了更令人鼓舞的结果，但它们表现出高度的可变性，并不总是能改善组织功能。为了提高干细胞的疗效，我们评估了机械记忆是否可以指导细胞反应。我们假设，在软基质上进行机械预处理（软预培养）将延迟脂肪来源干细胞（ASC）向促纤维化表型的转变，从而扩大其再生潜能，并改善复杂组织环境中的愈合效果。从大鼠和人皮下脂肪中分离的原代 ASC 表现出机械记忆，这表现为在软预培养两周后，细胞对刚度的反应延迟，与在硬基底上的细胞相比，细胞面积、肌动蛋白一致性和细胞外基质产生减少。将软预培养的 ASC 注射到我们的创伤后肘挛缩大鼠模型中，通过关节力学评估，可减少前囊纤维化的组织学证据，并增加肘的活动范围。这些发现表明，通过在细胞扩增过程中策略性地控制培养环境来利用机械记忆，可能会提高针对纤维化的基于干细胞疗法的疗效。
