Scalable manufacture of therapeutic mesenchymal stromal cell products on customizable microcarriers in vertical wheel bioreactors that improve direct visualization, product harvest, and cost

BACKGROUND AIMS

Human mesenchymal stromal cells (hMSCs) and their secreted products show great promise for treatment of musculoskeletal injury and inflammatory or immune diseases. However, the path to clinical utilization is hampered by donor-tissue variation and the inability to manufacture clinically relevant yields of cells or their products in a cost-effective manner. Previously we described a method to produce chemically and mechanically customizable gelatin methacryloyl (GelMA) microcarriers for culture of hMSCs. Herein, we demonstrate scalable GelMA microcarrier-mediated expansion of induced pluripotent stem cell (iPSC)-derived hMSCs (ihMSCs) in 500 mL and 3L vertical wheel bioreactors, offering several advantages over conventional microcarrier and monolayer-based expansion strategies.

METHODS

Human mesenchymal stromal cells derived from induced pluripotent cells were cultured on custom-made spherical gelatin methacryloyl microcarriers in single-use vertical wheel bioreactors (PBS Biotech). Cell-laden microcarriers were visualized using confocal microscopy and elastic light scattering methodologies. Cells were assayed for viability and differentiation potential in vitro by standard methods. Osteogenic cell matrix derived from cells was tested in vitro for osteogenic healing using a rodent calvarial defect assay. Immune modulation was assayed with an in vivo peritonitis model using Zymozan A.

RESULTS

The optical properties of GelMA microcarriers permit noninvasive visualization of cells with elastic light scattering modalities, and harvest of product is streamlined by microcarrier digestion. At volumes above 500 mL, the process is significantly more cost-effective than monolayer culture. Osteogenic cell matrix derived from ihMSCs expanded on GelMA microcarriers exhibited enhanced in vivo bone regenerative capacity when compared to bone morphogenic protein 2, and the ihMSCs exhibited superior immunosuppressive properties in vivo when compared to monolayer-generated ihMSCs.

CONCLUSIONS

These results indicate that the cell expansion strategy described here represents a superior approach for efficient generation, monitoring and harvest of therapeutic MSCs and their products.

Inducible dominant negative ErbB2 rat spermatogonial line for generation of transgenic rat model and dissecting ERBB2 tyrosine kinase mediated pathways

AIM

The ERBB2 receptors tyrosine kinase, also known as HER2/Neu, play an essential role in early organism development and modulation of cell behavior in varieties of tissue in an adult organism. Our aim was the generation of transgenic rat spermatogonial line capable of inducible expression of a dominant negative form of the ERBB2 protein in vitro and the transgenic rat as an animal model for dissection of the ERBB2 mediated signaling in vitro and in vivo.

MATERIALS AND METHODS

Donor derived rat spermatogonial stem cells that express green fluorescence protein and inducible ERT2CreERT2 recombinase were modified with Sleeping Beauty transposon-based vector that express truncated kinase deficient form of the ERBB2 receptor upon Cre mediated recombination. Clonally selected spermatogonial cell lines were extensively tested in vitro. Animals were generated via spermatogonia mediated transgenesis by transplantation of clonal cell line into testes of chemically sterilized recipients. Obtained progeny were tested for inducibility in vivo and served as donors of spermatogonia for downstream analysis.

RESULTS

We obtained animals and clonally derived spermatogonial stem cell lines that express an inducible dominant negative form of the ERBB2 protein. Isogenic nature of induced and uninduced cells allows most accurate morphological and molecular comparison of cells affected by the interruption of normal function of the ERBB2 receptor and cellular dynamics in vitro and in vivo.

CONCLUSIONS

Clonally derived spermatogonial stem cell lines that express an inducible dominant negative form of ErbB2 demonstrated an obvious difference in morphological appearance and growth kinetics of induced cells comparing to uninduced ones. Western blot analysis of induced and uninduced cells revealed significant differences in presence and phosphorylation state of several tested important proteins involved in the ERBB2 mediated signal transduction, such as S6 ribosomal protein; AKT (the serine/threonine kinase also known as protein kinase B); and three protein kinases that participate in the RAS-RAF-MEK-ERK signal transduction cascade PRAS40, MEK, ERK1/2.

[Biochemical bases of melanogenesis and ways of its regulation]

Results of melanogenesis biochemical investigations as a complex multi-stage and interdependent process of biosynthesis of vital product--melanin have been generalized. The regulating influence of genetic, neurohumoral and other factors on synthesis of this biopolymer has been shown.