Hypoxia Induces Stem Cell Gene Expression, Protein Production and Cell Surface Markers

Histogen, Inc., a regenerative medicine company developing solutions based on the products of newborn cells grown under embryonic conditions, will present new findings today at the International Conference on Stem Cell Engineering (ICSCE). Analysis of the cells grown under Histogen’s proprietary conditions of hypoxia and low gravity show the expression of specific markers associated with embryonic stem cells.

Different cell types can be identified by unique profiles based on the genes they express, the proteins they produce, and markers that they have on their cell surface. Histogen has discovered that, under growth conditions of 2-5% oxygen (hypoxia) and low gravity, safe and non-controversial newborn skin cells (fibroblasts) acquire the profile of pluripotent stem cells.

“Over 5,000 genes are differentially expressed by these cells, as compared to fibroblasts grown under traditional conditions,” said Dr. Gail K. Naughton, CEO and Chairman of the Board at Histogen. “What we are seeing is a shift in the profile of these cells to one that is more embryonic-like, more similar to stem cells than fibroblasts.”

DNA microarray analysis revealed that, under hypoxic culture conditions, fibroblasts upregulate the expression of key embryonic stem cell markers including Oct4, Nanog, and Sox2.  These specific genes are known to be critical in the generation of induced pluripotent stem cells. A number of other stem cell-associated markers, such as Brachyury, Gata4, CCR4, LIN28 and Nodal FGF5 were also expressed at higher levels in the hypoxic cultures as compared to fibroblasts grown under normal oxygen levels.

These studies suggest hypoxic culture of somatic cells in large-scale bioreactor systems is a potentially feasible and efficient method for obtaining and producing adequate amounts of pluripotent stem cells and associated factors for clinical regenerative medicine applications. 

“Reprogramming adult, differentiated somatic cell types through chemical manipulation or genetic transfection to transform the cells into a dedifferentiated, pluripotent stem cell phenotype has been the focus of many recent studies,” said Dr. Jonathan Mansbridge, Chief Scientific Officer at Histogen. “Although these experiments have demonstrated the ability to induce cells back to a pluripotent state, the methods used have raised considerable issues regarding mutagenicity and clinical safety.  We now have preliminary evidence that, by altering the oxygen levels under which neonatal fibroblasts are cultured, there is potential for a viable pluripotent stem cell source that would be free of these issues.”
 
Human extracellular matrix (hECM) compositions produced under the hypoxia/microgravity conditions discussed here are covered by pending US patent #2010/0047305. "Induction of Stem Cell Marker Expression in Human Dermal Fibroblasts in Hypoxic Culture Conditions" will be presented by Dr. Mansbridge at the ICSCE event, taking place May 2-5, 2010 in Boston, Mass.