Isolation, biodistribution and safety assessment of human adipose-derived mesenchymal stem cells

by Alexey Bersenev on August 26, 2011 · 0 comments

in adipose, mesenchymal

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Human adipose tissue is a clinically significant source of stem and progenitor cells for therapies. There are many ongoing clinical trials, which involve adipose-derived stem cells. There is a variety of protocols for isolation different cell population from adipose tissue. Unfortunately, the field is still lacking of consensus and standards for isolation and preclinical assessment of adipose-derived stem cells.

Today, I’d like to share 2 studies, which provide protocols for isolation and safety assessment in vivo of human adipose-derived mesenchymal stem cells (AMSC).

The first study provides a protocol for high efficient isolation of AMSC:

We demonstrate here a method by isolating hADSCs from abdominal subcutaneous adipose tissue harvested during caesarian section. The hADSCs were isolated from human adipose tissue by collagenase digestion and adherence to flasks.

The yield reached around 1 x 106 hADSCs per gram adipose tissue. The following comprehensive identification and characterization illustrated pronounced features of mesenchymal stem cells (MSCs). The fibroblast-like hADSCs exhibited typical ultrastructure details for vigorous cell activities. Karyotype mapping showed normal human chromosome. With unique immunophenotypes they were positive for CD29, CD44, CD73, CD105 and CD166, but negative for CD31, CD34, CD45 and HLA-DR.

The second study demonstrates the survival, distribution and safety of human AMSC in in vivo assays:

We subcutaneously injected human AMSCs from different human donors into immunodeficient SCID mice over both short- (2 and 4 mo) and long- (17 mo) term in young, and aged tumor-prone mice. Presence of human cells was studied by immunohistochemistry and polymerase chain reaction analysis in all organs of injected mice.

Subcutaneously injected AMSCs did not form teratomas at any time point. They did not migrate but remained at the site of injection regardless of animal age, and did not fuse with host cells in any organ examined. AMSCs survived in vivo for at least 17 mo after injection, and differentiated into fibroblasts of the subdermic connective tissue and into mature adipocytes of fat tissue, exclusively at the site of injection.

In order to challenge AMSC behavior the authors also use so-called “tumor-prone mice” as recipients:

In order to study the behavior of transplanted human AMSCs in a tumor-prone microenvironment, isolated human AMSCs were subcutaneously transplanted into 1-year-old NOD/SCID mice, a strain which is prone to develop tumors with aging. In consequence, this strain has a mean age lifespan of only 8.5 mo under pathogen-free conditions, although animals can live more than a year.

…the tumors were not formed by human transplanted cells, as demonstrated by both immunohistochemistry using a monoclonal anti-human mitochondria antibody (Figure 4C) and by detection of the human-specific β2 microglobulin gene by PCR.

Of course, presented in vivo assays have some limitations. For example, they didn’t test AMSC in conditions of functional human immune system. But, I think, this preclinical model give us some useful insights into safety of AMSC-based therapies.

I think these studies worth a look.

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