Tissue organoids are a promising technology that may accelerate development of the societal and NIH mandate for precision medicine. Here we describe a robust and simple method for generating cerebral organoids (cOrgs) from human pluripotent stem cells by using a chemically defined hydrogel material and chemically defined culture medium. By using no additional neural induction components, cOrgs appeared on the hydrogel surface within 10-14 days, and under static culture conditions, they attained sizes up to 3 mm in greatest dimension by day 28. Histologically, the organoids showed neural rosette and neural tube-like structures and evidence of early corticogenesis. Immunostaining and quantitative reverse-transcription polymerase chain reaction demonstrated protein and gene expression representative of forebrain, midbrain, and hindbrain development. Physiologic studies showed responses to glutamate and depolarization in many cells, consistent with neural behavior. The method of cerebral organoid generation described here facilitates access to this technology, enables scalable applications, and provides a potential pathway to translational applications where defined components are desirable. STEM CELLS TRANSLATIONAL MEDICINE 2016;5:970-979 SIGNIFICANCETissue organoids are a promising technology with many potential applications, such as pharmaceutical screens and development of in vitro disease models, particularly for human polygenic conditions where animal models are insufficient. This work describes a robust and simple method for generating cerebral organoids from human induced pluripotent stem cells by using a chemically defined hydrogel material and chemically defined culture medium. This method, by virtue of its simplicity and use of defined materials, greatly facilitates access to cerebral organoid technology, enables scalable applications, and provides a potential pathway to translational applications where defined components are desirable.

Three-dimensional (3D) cell culture platforms are increasingly utilized due to their ability to more closely mimic the in vivo microenvironment compared to traditional two-dimensional methods. Limitations of currently available 3D materials include lack of cell attachment, long polymerization times, and inclusion of undefined xenobiotics, and cytotoxic cross-linkers. Evaluated here is a unique hydrogel comprised of polyelectrolytic complex (PEC) fibers formed by hyaluronic acid and chitosan (CT). When hydrated with fetal bovine serum containing human mesenchymal stem/stromal cells (hMSCs), a hydrogel with an elastic modulus of 264±38 Pa formed in seconds with cells distributed throughout the matrix. Scanning electron microscopy showed a lattice-like meshwork of PEC fibers forming irregular compartments. hMSCs showed 48% viability during the first 24 h, with cell populations thereafter reaching a steady state for 14 days. hMSCs in the matrix were induced to differentiate to chondrogenic, osteogenic, and adipogenic phenotypes. Emergent features, at days 56 and 70, consisted of chondrogenesis on the surface of hydrogels induced to osteogenic and adipogenic phenotypes. Results indicate that this matrix may be useful for tissue engineering and disease modeling applications.

Background Potent immunomodulatory effects have been reported for mesenchymal stem/stromal cells (MSCs), multipotent adult progenitor cells (MAPCs), and fibroblasts. However, side-by-side comparisons of these cells specifically regarding immunophenotype, gene expression, and suppression of proliferation of CD4+ and CD8+ lymphocyte populations have not been reported. Methods We developed MAPC and MSC lines from rhesus macaque bone marrow and fibroblast cell lines from rhesus dermis and assessed phenotypes based upon differentiation potential, flow cytometric analysis of immunophenotype, and quantitative RT-PCR analysis of gene expression. Using allogeneic lymphocyte proliferation assays, we compared the in vitro immunomodulatory potency of each cell type. Results and Conclusions Extensive phenotypic similarities exist among each cell type, although immunosuppressive potencies are distinct. MAPCs are most potent, and fibroblasts are the least potent cell type. All three cell types demonstrated immunomodulatory capacity such that each may have potential therapeutic applications such as in organ transplantation, where reduced local immune response is desirable.

The potential of mesenchymal stromal cells (MSCs) to inhibit anti-tumor immunity is becoming increasingly well recognized, but the precise steps affected by these cells during the development of an anti-tumor immune response remain incompletely understood. Here, we examined how MSCs affect the steps required to mount an effective anti-tumor immune response following administration of adenovirus-Fas ligand (As-FasL) in the Lewis Lung carcinoma (LL3) model. Administration of bone marrow derived MSCs with LL3 cells accelerated tumor growth significantly. MSCs inhibited the inflammation induced by Ad-FasL in the primary tumors, precluding their rejection; MSCs also reduced the consequent expansion of tumor-specific T cells in the treated hosts. When immune T cells were transferred to adoptive recipients, MSCs impaired, but did not completely abrogate the ability of these T cells to promote elimination of secondary tumors. This impairment was associated with a modest reduction in tumor infiltrating T cells, with a significant reduction in tumor-infiltrating macrophages, and a reorganization of the stromal environment. Our data indicate that MSCs in the tumor environment reduce the efficacy of immunotherapy by creating a functional and anatomic barrier that impairs inflammation, T-cell priming and expansion, and T-cell function - including recruitment of effector cells.

The characteristics of canine IL-17-producing cells are incompletely understood. Expression of mRNA encoding orthologs of IL-17 and the IL-17 receptor has been documented in tissues from dogs with arthritis, inflammatory bowel disease, and lymphoma; however, no associations have been found between IL-17 gene expression and disease phenotype in these conditions. Robust assessment of the role of IL-17-producing cells in dogs will require measuring the frequency of these cells in health and disease in balance with other lymphocyte subsets. The aim of this study was to confirm that the T-cell IL-17 response in dogs is evolutionarily conserved. Canine peripheral blood mononuclear cells were stimulated with Concanavalin A with or without polarizing cytokines. We used a canine specific IL-17 ELISA and flow cytometry to identify IL-17-producing T cells. Accumulation of intracellular IL-17 was observed in stimulated CD4 and CD8 T cells. The addition of pro-inflammatory cytokines appeared to enhance polarization of canine CD4 T cells to the Th17 phenotype. Conversely, the addition of IL-2 in the presence of TGF-β resulted in expansion of Treg cells. We conclude that canine IL-17-producing cells behave similarly to those from humans and mice when stimulated with mitogens and polarized with pro-inflammatory or immune regulatory cytokines.

Despite holding great therapeutic potential, existing protocols for in vitro chondrogenesis and hyaline cartilage production from human induced pluripotent stem cells (hiPSC) are laborious and complex with unclear long-term consequences. Here, we developed a simple xeno- and feeder-free protocol for human hyaline cartilage production in vitro using hydrogel-cultured multi-tissue organoids (MTOs). We investigate gene regulatory networks during spontaneous hiPSC-MTO differentiation using RNA sequencing and bioinformatic analyses. We find the interplays between BMPs and neural FGF pathways are associated with the phenotype transition of MTOs. We recognize TGF-beta/BMP and Wnt signaling likely contribute to the long-term maintenance of MTO cartilage growth and further adoption of articular cartilage development. By comparing the MTO transcriptome with human lower limb chondrocytes, we observe that the expression of chondrocyte-specific genes in MTO shows a strong correlation with fetal lower limb chondrocytes. Collectively, our findings describe the self-organized emergence of hyaline cartilage in MTO, its associated molecular pathways, and its spontaneous adoption of articular cartilage development trajectory.

In the transplant community, natural suppressive cells derived from animals offer vast advantages over traditional chemical immunosuppressive agents that have very harsh side effects on both the transplant and the patient. The bulk of this research has focused on T regulatory cells (Tregs), given their known role of quelling and suppressing immune responses to natural infection. Other cells, such as mesenchymal stem cells (MSC), have also been observed to exert suppressive capabilities. As therapeutic immunomodulatory cells, MSCs have an advantage over Tregs in that they are much less immunogenic and may potentially be utilized from allogeneic derivations whereas Tregs require patient specific development in the form of autogenic isolations from blood, which greatly limits the available supply. In addition to MSCs, fibroblasts and multipotent adult progenitor cells (MAPCs), which are phenotypically very similar to MSCs, have each been considered to have immunomodulatory potential but mechanisms are poorly understood. Using Rhesus bone marrow-derived MSC and MAPC and dermal fibroblasts we showed that all 3 types of cells strongly (80-90%) inhibited proliferation of (αCD3 stimulated) CD4 and CD8 T-lymphocytes in an in vitro assay. Suppression was maximal with 1:1 cell ratios and effects diminished with serial dilution of test cells. The findings suggest that all 3 lineages have potential as an alternative to Tregs for immunosuppression in organ transplantation.