Florian Sommer

Ascorbic Acid Enhances Adipogenesis of Bone Marrow-Derived Mesenchymal Stromal Cells

A prerequisite to successfully engineer cell-based adipose tissue surrogates is the evaluation of in vitro culture conditions that facilitate expansion of primary precursor cells under retention of their adipogenic potential and that enable a large fraction of the heterogeneous cell pool to undergo adipogenesis upon respective stimuli. Ascorbic acid (AA) was reported to enhance differentiation of precursor cells into various mesenchymal cell types. Thus, the aim of the current study was to evaluate the influence of AA on hormonally induced adipogenesis of bone marrow-derived mesenchymal stromal cells (BMSCs) in vitro when supplemented during cell propagation and/or adipogenic differentiation. BMSCs were isolated from rat bone marrow, propagated, and hormonally induced to undergo adipogenesis. Supplementation of AA from the time of induction increased the fraction of BMSCs differentiating into adipocytes and glycerol-3-phosphate dehydrogenase activity up to 2-fold. Furthermore, administration of AA already during propagation had an even larger effect with an up to 8-fold increase in adipogenic markers. Assessment of collagen accumulation suggested that the observed effects might be attributed to an enhanced collagen synthesis during propagation. The presented results demonstrate AA as a potent medium component able to enhance adipogenic conversion of BMSCs, especially when administered during cell propagation.

Ocular tissue engineering

In the early 1990s, tissue engineering emerged as a new concept to overcome the problem of tissue and organ failure. It proposed to supply engineered, yet biological, organ and tissue substitutes. It was anticipated that this technology would soon allow us to overcome donor shortages and graft rejection, the major limitations of tissue and organ transplantation. Tissue engineering approaches that were developed on the basis of this paradigm relied on the use of cells and stem cells, preferably of autologous origin, the application of growth factors and cytokines, the design of biodegradable scaffolds and bioreactor technology1, 2.

FACS as useful tool to study distinct hyalocyte populations

Hyalocytes, the cells of the vitreous body, are assumed to be involved in physiological as well as patho-physiological processes within the eye. However, current knowledge about the cells is still limited. As different morphological types of hyalocytes are described in the literature, it seems reasonable to try to isolate individual populations prior to characterization of single cell types. To achieve this, the present study investigated the utility of fluorescence activated cell sorting (FACS) for hyalocyte separation. Subsequent to digestion of vitreous bodies using collagenase, the resulting cell suspension was analyzed and separated using FACS without any additional staining. Two-parameter dot plots of forward scatter (indicating size) against sideward scatter (indicating granularity) showed two distinct cell populations; staining with propidium iodide confirmed that both populations represent living cells. After sorting, cells of both populations were seeded on tissue culture plastic (tissue culture treated polystyrene). Only one population attached and proliferated, whereas the other population was non-adherent. Even when seeding the native cell mix, only one population of cells was observed after two passages, as indicated by FACS. Furthermore, ascorbic acid increased proliferation of these cells similarly to the proliferation of the separated cell population. These data point out that only one of the two populations adheres and proliferates on tissue culture plastic. To conclude, the established isolation technique allows for separation of clearly defined hyalocyte populations. Moreover, clear hints were obtained that only one of the two populations adheres and proliferates under the commonly applied culture conditions.

Contents Vol. 189, 2009

Stem Cells and Tissue Engineering A. Bader, Leipzig E-Mail: augustinus.bader@bbz.uni-leipzig.de S.F. Badylak, Pittsburgh, Pa. E-Mail: badylaks@msx.upmc.edu A. Müller, Würzburg E-Mail: albrecht.müller@mail.uni-wuerzburg.de A. Ratcliffe, San Diego, Calif. E-Mail: anthonyratcliffe@synthasome.com A.M. Wobus, Gatersleben E-Mail: wobusam@ipk-gatersleben.de Neurosciences M. Frotscher, Freiburg i.Br. E-Mail: frotsch@sun2.ruf.uni-freiburg.de W.L. Neuhuber, Erlangen E-Mail: winfried.neuhuber@rzmail.uni-erlangen.de