Optimization of repeated freeze-thaw and ultrasonication for collection of lysate of adipose-derived stem cells / 中国组织工程研究

ABSTRACT

BACKGROUND: It has been believed mesenchymal stem cells (MSCs) play a role in treatment through paracrine mechanism. Various side effects such as embolism, tumorigenesis and immunological reaction caused by direct injection of MSCs can be avoided by extracting MSC lysate. However, there is a larger difference in current collection methods and standards of MSC lysate. OBJECTIVE: To compare repeated freeze-thaw and ultrasonication for the collection of lysate of MSCs. METHODS: Adipose-derived mesenchymal stem cells (ADMSCs) were isolated from the abdominal subcutaneous fat of healthy individuals, and purified with adherence screening method, followed by in vitro amplification using fetal bovine serum medium. The common surface makers of these cells were tested by flow cytometry (1×109, 2×109, 4×109/L). Repeated freeze-thaw and ultrasonication were employed for cell cytoclasis at three different densities respectively in saline and double distilled water, and a comprehensive comparison was performed on cytoclasis rate and the content of protein in cell lysate between the two methods. RESULTS AND CONCLUSION: (1) ADMSCs obtained from in vitro isolated human adipose tissue grew in a swirl or radial pattern with a homogenous size and neat arrangement. CD44, CD90, CD105 and other commonly used surface markers were highly expressed. (2) The study for optimization of lysate collection revealed that the higher cell density implicated a longer time for cell wall disruption and cytoclasis, as well as significantly increased cytoclasis rate. (3) BCA protein assay showed that the highest content of protein was obtained in saline solvent using ultrasonication method. Comprehensive analysis on the results leads to a conclusion that ultrasonication method with saline as the solvent is the optimized method for extraction of ADMSCs lysate, and the cell concentration of less than 4×109/L is recommended.