Safety of adipose-derived stem cells and collagenase in fat tissue preparation.

UNLABELLED: Recently, various studies using adipose-derived stem cells (ADSCs) have been performed. However, the safety of ADSCs has not been determined, and protocols for isolating ADSCs have not been established. This study evaluated the activity and toxicity of residual collagenase in isolated ADSCs and the carcinogenicity of these cells. It evaluated the current use of ADSC-related procedures in South Korea as reference data for the authors' studies. The study surveyed 100 private plastic surgical clinics, 68 plastic surgery departments at general and university hospitals, and 5 biotechnology companies by telephone. Among these, 14 institutions were surveyed using a more detailed questionnaire about ADSC-related procedures and methods of processing adipose tissue. The survey also evaluated the residual collagenase activity during five washes of the ADSC isolation procedure with furyl acryloyl-Leu-Gly-Pro-Ala (FALGPA) and ninhydrin assays. A 4-week toxicity study in non-obese diabetes/severe combined immunodeficiency (NOD/SCID) mice was performed as well as a tumorigenicity study in BALB/c-nu mice using ADSCs from the first and third washes. According to the findings, ADSC-related procedures were performed in 16 % of the private clinics and 14.7 % of the general hospitals surveyed. Among the 14 institutions, 0.1 % type 1 collagenase was used most frequently, and three washes generally were performed. After the first wash, residual collagenase activity was the same as in the blank group (saline only). No toxicity resulting from residual collagenase or tumorigenicity associated with the ADSCs was observed. The results of the current study may be beneficial for establishing safe ADSC isolation protocols and can be used as fundamental data for clinical applications involving ADSCs. LEVEL OF EVIDENCE II: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .