Biological Activities Encoded by the Murine Mesenchymal Stem Cell Transcriptome Provide a Basis for Their Developmental Potential and Broad Therapeutic Efficacy

Abstract

We used serial analysis of gene expression to catalog the transcriptome of murine mesenchymal stem cells (MSCs) enriched from bone marrow by immunodepletion. Interrogation of this database, results of which are delineated in the appended databases, revealed that immunodepleted murine MSCs (IDmMSCs) highly express transcripts encoding connective tissue proteins and factors modulating T-cell proliferation, inflammation, and bone turnover. Categorizing the transcriptome based on gene ontologies revealed the cells also expressed mRNAs encoding proteins that regulate mesoderm development or that are characteristic of determined mesenchymal cell lineages, thereby reflecting both their stem cell nature and differentiation potential. Additionally, IDmMSCs also expressed transcripts encoding proteins regulating angiogenesis, cell motility and communication, hematopoiesis, immunity and defense as well as neural activities. Immunostaining and fluorescence-activated cell sorting analysis revealed that expression of various regulatory proteins was restricted to distinct subpopulations of IDmMSCs. Moreover, in some cases, these proteins were absent or expressed at reduced levels in other murine MSC preparations or cell lines. Lastly, by comparing their transcriptome to that of 17 other murine cell types, we also identified 43 IDmMSC-specific transcripts, the nature of which reflects their varied functions in bone and marrow. Collectively, these results demonstrate that IDmMSC express a diverse repertoire of regulatory proteins, which likely accounts for their demonstrated efficacy in treating a wide variety of diseases. The restricted expression pattern of these proteins within populations suggests that the cellular composition of marrow stroma and its associated functions are more complex than previously envisioned.

Biochemical Heterogeneity of Mesenchymal Stem Cell Populations: Clues to their Therapeutic Efficacy

“…2,42,43 These analyses revealed that the MSC transcriptome reflected the developmental potential of the cells as depicted initially by the mesengenic process. 6 For example, both murine and human MSCs expressed a variety of developmentally regulated transcripts that play a role in the specification of mesoderm as well as transcripts characteristic of skeletal, adipose, muscle and endothelial tissue.…”

“…In the process of validating these findings it became evident that expression of many of these proteins was restricted to specific subpopulations. 43 Moreover, these expressed proteins were found to impart unique functional properties onto MSCs.…”

Molecular profile of mouse stromal mesenchymal stem cells

“…Networks have not been emphasized in previous transcriptomic studies on stem cells (4,21,27,33,35,38,40,42,43,46,49). The networks described in the present study may serve as a basis for future experiments.…”

A SAGE View of Mesenchymal Stem Cells

“…A detailed description of the aforementioned SAGE databases has been published previously (22)(23)(24). Analysis of these databases revealed that the MSC transcriptome reflected both the developmental potential of MSCs as depicted by the mesengenic process and a capacity to regulate a broad array of biological processes important for bone and marrow function (Fig.…”

“…In the latter case, MSCs were also found to express different classes of regulatory proteins important for angiogenesis, cell motility and communication, hematopoiesis, neural activities and immunity and defense. In the process of validating the SAGE data, it became evident that expression of different regulatory proteins was restricted to specific subpopulations of MSCs (24). Accordingly, we hypothesized that these subpopulations exhibit unique biological characteristics and as such contribute to the broad therapeutic efficacy of MSCs at the population level.…”