Human mesenchymal stem cell spheroids in fibrin hydrogels exhibit improved cell survival and potential for bone healing

• Published in: Cell and tissue research Vol. 357; no. 1; pp. 91 - 99
• Main Authors: Murphy, Kaitlin C, Fang, Sophia Y, Leach, J. Kent
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.07.2014; Springer Berlin Heidelberg; Springer; Springer Nature B.V
• Subjects: apoptosis; Biological products; Biomedical and Life Sciences; Biomedicine; bone formation; Bone Regeneration - physiology; Bones; Cell Differentiation; Cell Proliferation - physiology; Cell Survival - physiology; cell viability; Cells, Cultured; Cellular biology; Exhibitions; Fibrin; Fractures; gels; Health aspects; Human Genetics; Humans; hydrocolloids; Hydrogels; immune response; Mesenchymal Stromal Cells - cytology; Mesenchymal Stromal Cells - metabolism; Molecular Medicine; Monomolecular films; Osteogenesis - physiology; oxygen; Proteomics; Regular Article; secretion; Spheroids, Cellular; Stem cells; Vascular endothelial growth factor; vascular endothelial growth factors; Mesenchymal stem cell; Osteogenic potential; Fibrin; Spheroid; Cell survival
• ISSN: 0302-766X; 1432-0878
• DOI: 10.1007/s00441-014-1830-z

Mesenchymal stem cells (MSCs) have great therapeutic potential for the repair of nonhealing bone defects, because of their proliferative capacity, multilineage potential, trophic factor secretion and lack of immunogenicity. However, a major challenge to the translation of cell-based therapies into clinical practice is ensuring their survival and function upon implantation into the defect site. We hypothesize that forming MSCs into more physiologic three-dimensional spheroids, rather than employing dissociated cells from two-dimensional monolayer culture, will enhance their survival when exposed to a harsh microenvironment but maintain their osteogenic potential. MSC spheroids were formed by using the hanging drop method with increasing cell numbers. Compared with larger spheroids, the smallest spheroids, which contained 15,000 cells, exhibited increased metabolic activity, reduced apoptosis and the most uniform distribution of proliferating cells. Spheroids were then entrapped in fibrin gels and cultured in serum-free medium and 1 % oxygen. Compared with identical numbers of dissociated MSCs in fibrin gels, spheroids exhibited significantly reduced apoptosis and secreted up to 100-fold more vascular endothelial growth factor. Moreover, fibrin gels containing spheroids and those containing an equivalent number of dissociated cells exhibited similar expression levels of early and late markers of osteogenic differentiation. Thus, MSC spheroids exhibit greater resistance to apoptosis and enhanced proangiogenic potential while maintaining similar osteogenic potential to dissociated MSCs entrapped in a clinically relevant biomaterial, supporting the use of MSC spheroids in cell-based approaches to bone repair.