A Novel Xenogeneic Co-Culture System to Examine Neuronal Differentiation Capability of Various Adult Human Stem Cells

Background: Targeted differentiation of stem cells is mainly achieved by the sequential administration of defined growth factors and cytokines, although these approaches are quite artificial, cost-intensive and time-consuming. We now present a simple xenogeneic rat brain co-culture system which supports neuronal differentiation of adult human stem cells under more in vivo-like conditions. Methods and Findings: This system was applied to well-characterized stem cell populations isolated from human skin, parotid gland and pancreas. In addition to general multi-lineage differentiation potential, these cells tend to differentiate spontaneously into neuronal cell types in vitro and are thus ideal candidates for the introduced co-culture system. Consequently, after two days of co-culture up to 12% of the cells showed neuronal morphology and expressed corresponding markers on the mRNA and protein level. Additionally, growth factors with the ability to induce neuronal different iation in stem cells could be found in the media supernatants of the co-cultures. Conclusions: The co-culture system described here is suitable for testing neuronal differentiation capability of numerous types of stem cells. Especially in the case of human cells, it may be of clinical relevance for future cell-based therapeutic applications

Phenotypic indications that human sweat glands are a rich source of nestin-positive stem cell populations

Background We have recently shown that the expression of nestin, a progenitor/stem cell marker protein, is localized in different mesenchymal compartments in human skin including the sweat gland stroma. Objectives As other exocrine glands are recognized sources of multipotent stem cell populations with potential for multilineage differentiation, it was our aim to isolate, expand and characterize glandular stem cells from human sweat glands. Methods Isolation of human sweat glands was based on mechanical and enzymatic digestion of axillary skin. Cultivation was performed on collagen-coated cell culture dishes and the resulting cell population was investigated at the protein and mRNA level. Results Outgrowing cells of isolated sweat glands showed a high-proliferation activity and were characterized by nestin expression in more than 80% of the cells. These sweat gland stem cells could be maintained in culture for long periods of time and showed spontaneous differentiation into cells representative of the different germ layers. Conclusions This pilot study provides the first, simple protocol for the isolation of adult human nestin-positive stem cells from the sweat gland mesenchyme, which promises to provide an easily accessible and abundantly available, autologous source of multipotent stem cells for cell-based regenerative medicine applications