Critical steps in the isolation and expansion of adipose-derived stem cells for translational therapy

Abstract

Since the discovery of adipose-derived stem cells (ASCs), there have been high expectations of their putative clinical use. Recent advances support these expectations, and it is expected that the transition from pre-clinical and clinical studies to implementation as a standard treatment modality is imminent. However ASCs must be isolated and expanded according to good manufacturing practice guidelines and a basic assurance of quality, safety, and medical effectiveness is needed for authorisation by regulatory agencies, such as European Medicines Agency and US Food and Drug Administration. In this review, a collection of studies investigating the influence of different steps of the isolation and expansion protocol on the yield and functionality of ASCs has been presented in an attempt to come up with best recommendations that ensure potential beneficial clinical outcome of using ASCs in any therapeutic setting. If the findings confirm the initial observations of beneficial effects of ASCs, the path is paved for implementing these ASC-based therapies as standard treatment options.

Comparison of human platelet lysate alternatives using expired and freshly isolated platelet concentrates for adipose-derived stromal cell expansion

“…This study would also have benefitted from growth factor analysis as platelet-derived growth factors are known to play pivotal roles in cellular proliferation, differentiation and migration (62)(63)(64). Furthermore, ASCs expanded in FBS have had adverse immunogenic effects (4,65) when transplanted back into patients. In order to assess the immunomodulatory effects of ASCs expanded in the different pHPL alternatives, functional experiments should be performed both in vitro and in vivo.…”

“…These properties have resulted in the use of ASCs for cellular therapies, as evidenced by the fact that their therapeutic effect is being assessed in over 180 clinical trials (2,3). Of those clinical trials that have listed their expansion conditions and media preparation (4), the majority make use of foetal bovine serum (FBS), which has had adverse reactions on patients receiving the cells (4). While FBS is essential for ASC attachment, expansion and maintenance, it does harbour the potential for xenoimmunisation and the transmission of zoonotic contaminants (5).…”

“…Furthermore, the preparation of ASCs for cellular therapies needs to be compliant with good manufacturing practices (GMP). This can be achieved, in part, by changing to chemically defined, xeno-free or human bloodderived alternatives (4,6). These human blood-derived alternatives include human serum, platelet-rich plasma, platelet-poor plasma and platelet lysate (7)(8)(9)(10).…”

Biological characteristics and karyotiping of a new isolation method for human adipose mesenchymal stem cells in vitro

“…Prior to MSCs from bone marrow, ASCs derived from adipose tissue occur at a 100-1000-fold higher frequency within adipose tissue on a volume basis with minimally invasive and less painful adipose tissue harvesting procedure [3]. In addition, ASCs have been shown to secrete many growth factors such as hepatocyte growth factor (HGF) and release cytokines [4].…”

“…And the therapeutic appeal of ASCs is further underscored by the results from the numerous animal experiments, small clinical trials and case-reports [4]. It is also a trend that the isolation and expansion of ASCs should be in accordance to good manufacturing practice (GMP)-guidelines and national legislation.…”