Roxanne L. Reger

Multipotent stromal cells from human marrow home to and promote repair of pancreatic islets and renal glomeruli in diabetic NOD/scid mice

We tested the hypothesis that multipotent stromal cells from human bone marrow (hMSCs) can provide a potential therapy for human diabetes mellitus. Severe but nonlethal hyperglycemia was produced in NOD/scid mice with daily low doses of streptozotocin on days 1–4, and hMSCs were delivered via intracardiac infusion on days 10 and 17. The hMSCs lowered blood glucose levels in the diabetic mice on day 32 relative to untreated controls (18.34 mM ± 1.12 SE vs. 27.78 mM ± 2.45 SE, P = 0.0019). ELISAs demonstrated that blood levels of mouse insulin were higher in the hMSC-treated as compared with untreated diabetic mice, but human insulin was not detected. PCR assays detected human Alu sequences in DNA in pancreas and kidney on day 17 or 32 but not in other tissues, except heart, into which the cells were infused. In the hMSC-treated diabetic mice, there was an increase in pancreatic islets and β cells producing mouse insulin. Rare islets contained human cells that colabeled for human insulin or PDX-1. Most of the β cells in the islets were mouse cells that expressed mouse insulin. In kidneys of hMSC-treated diabetic mice, human cells were found in the glomeruli. There was a decrease in mesangial thickening and a decrease in macrophage infiltration. A few of the human cells appeared to differentiate into glomerular endothelial cells. Therefore, the results raised the possibility that hMSCs may be useful in enhancing insulin secretion and perhaps improving the renal lesions that develop in patients with diabetes mellitus.

Stem/progenitor cells from bone marrow decrease neuronal death in global ischemia by modulation of inflammatory/immune responses

Human mesenchymal stromal cells (hMSCs) were injected into the hippocampus of adult mice 1 day after transient global ischemia. The hMSCs both improved neurologic function and markedly decreased neuronal cell death of the hippocampus. Microarray assays indicated that ischemia up-regulated 586 mouse genes. The hMSCs persisted for <7 days, but they down-regulated >10% of the ischemia-induced genes, most of which were involved in inflammatory and immune responses. The hMSCs also up-regulated three mouse genes, including the neuroprotective gene Ym1 that is expressed by activated microglia/macrophages. In addition, the transcriptomes of the hMSC changed with up-regulation of 170 human genes and down-regulation of 54 human genes. Protein assays of the hippocampus demonstrated increased expression in microglia/macrophages of Ym1, the cell survival factor insulin-like growth factor 1, galectin-3, cytokines reflective of a type 2 T cell immune bias, and the major histocompatibility complex II. The observed beneficial effects of hMSCs were largely explained by their modulation of inflammatory and immune responses, apparently by alternative activation of microglia and/or macrophages.

Evolving paradigms for repair of tissues by adult stem/progenitor cells (MSCs)

•  Paradigm I: the haematopoietic niche •  Paradigm II: engraftment/differentiation ‐  Early observations on engraftment and differentiation ‐  Technical challenges in testing paradigm II ‐  The impetus to test the paradigm II in clinical trials ‐  Tests of the paradigm II with local administrations ‐  Tests of paradigm II with systemic infusion •  Paradigm III: transient ‘quasi‐niches’ ‐  Unusual features of MSCs in culture ‐  Cross‐talk with injured tissues ‐  Modulation of inflammation in paradigm III ‐  Modulation of apoptosis in paradigm III ‐  Modulation of immune reactions ‐  Paradigm III and the similarities to paradigm I •  Conclusions/perspectives ‐  Why is administration of MSCs beneficial? ‐  Better assays for the potency of MSCs? ‐  Are MSCs pericytes? ‐  Therapies with recombinant proteins? ‐  Additional questions in developing therapies with MSCs

Multipotent mesenchymal stromal cells attenuate chronic inflammation and injury-induced sensitivity to mechanical stimuli in experimental spinal cord injury.

PURPOSE Previous reports established that after a contusion injury to the rat spinal cord, locomotor function was enhanced by the transplantation of cells from bone marrow referred to as either mesenchymal stem cells or multipotent mesenchymal stromal cells (MSCs). It has also been established that neural stem cells (NSCs) enhance locomotor function after transplantation into the injured rat spinal cord. However, the beneficial effects of NSCs are limited by graft-induced allodynia-like responses. Little is known about the effects of MSCs on sensory function in spinal cord injury. Therefore, the objective of this research was to determine whether transplantation of MSCs into the injured rat spinal cord induces allodynia-like responses. METHODS Contusion injuries of two different severities were induced in rats to examine the effects of transplantation with MSCs on sensorimotor deficits. The effects of MSCs on chronic inflammation were investigated, since inflammation is reported to have a role in the sensorimotor deficits associated with spinal cord injury. In addition, observations in other models suggest that MSCs possess immunosuppressive effects. RESULTS We found that in contrast to previous observations with the transplantation of neural stem cells, transplantation of MSCs did not induce allodynia. MSCs attenuated injury-induced sensitivity to mechanical stimuli but had no effect on injury-induced sensitivity to cold stimuli. MSCs also significantly attenuated the chronic inflammatory response as assayed by GFAP immunoreactivity for reactive astrocytes and ED1 immunoreactivity for activated macrophages/microglia. In addition, transplantation of MSCs increased white matter volumes and decreased cyst size in sections of the cord containing the lesion. CONCLUSION The results suggest that the sensorimotor enhancements produced by MSCs can at least in part be explained by anti-inflammatory/immunosuppressive effects of the cells, similar to such effects of these cells observed in other experimental models.

Intra-articular injection of human mesenchymal stem cells (MSCs) promote rat meniscal regeneration by being activated to express Indian hedgehog that enhances expression of type II collagen

OBJECTIVE Meniscal regeneration was previously shown to be enhanced by injection of mesenchymal stem/stromal cells (MSCs) but the mode of action of the MSCs was not established. The aim of this study was to define how injection of MSCs enhances meniscal regeneration. DESIGN A hemi-meniscectomy model in rats was used. Rat-MSCs (rMSCs) or human-MSCs (hMSCs) were injected into the right knee joint after the surgery, and PBS was injected into the left. The groups were compared macroscopically and histologically at 2, 4, and 8 weeks. The changes in transcription in both human and rat genes were assayed by species-specific microarrays and real-time RT-PCRs. RESULTS Although the number of hMSCs decreased with time, hMSCs enhanced meniscal regeneration in a manner similar to rMSCs. hMSCs injection increased expression of rat type II collagen (rat-Col II), and inhibited osteoarthritis progression. The small fraction of hMSCs was activated to express high levels of a series of genes including Indian hedgehog (Ihh), parathyroid hormone-like hormone (PTHLH), and bone morphogenetic protein 2 (BMP2). The presence of hMSCs triggered the subsequent expression of rat-Col II. An antagonist of hedgehog signaling inhibited the expression of rat-Col II and an agonist increased expression of rat-Col II in the absence of hMSCs. CONCLUSIONS Despite rapid reduction in cell numbers, intra-articular injected hMSCs were activated to express Ihh, PTHLH, and BMP2 and contributed to meniscal regeneration. The hedgehog signaling was essential in enhancing the expression of rat-Col II, but several other factors provided by the hMSCs probably contributed to the repair.

Differentiation and Characterization of Human MSCs

One of the hallmark characteristics of human MSCs (hMSCs) is their ability to differentiate into adipocytes, chondrocytes and osteocytes in culture. The default fate for hMSCs appears to be bone: if late-passage cultures are left in basic culture medium, the hMSCs will become confluent and produce mineral, an indication of bone formation. However, when grown under certain culture conditions or in media containing specific components, the cells can be driven to become a number of other specific cell types including neural cells, myocytes, and cardiomyocytes. The protocols given here are the basic differentiation procedures for inducing osteogenesis, adipogenesis, and chondrogenesis in cultures of hMSCs. Although there is still no clear consensus on the antigen expression pattern that will define hMSCs, a protocol is also presented for the flow cytometric analysis using a series of antibody panels. The analysis of these surface epitope patterns can aide in the isolation and characterization of hMSCs.

Rat marrow stromal cells rapidly transduced with a self-inactivating retrovirus synthesize L-DOPA in vitro.

Autologous bone marrow stromal cells engineered to produce 3,4,-dihydroxyphenylalanine (L-DOPA) can potentially be used as donor cells for neural transplantation in Parkinsons disease. Here, we examined the possibility of using several different promoters and either a self-inactivating retrovirus (pSIR) or standard retroviruses to introduce into marrow stromal cells (MSCs), the two genes necessary for the cells to synthesize L-DOPA. pSIR vectors were constructed using the mouse phosphoglycerate kinase-1 (PGK) promoter or the cytomegalovirus (CMV) promoter to drive expression of either a GFP reporter gene or a bicistronic sequence containing the genes for human tyrosine hydroxylase type I (TH) and rat GTP cyclohydrolase I (GC) separated by an internal ribosome entry site (IRES). rMSCs were successfully transduced with both standard retroviral vectors and pSIR containing the PGK promoter. Transduced rMSCs expressed GFP (90.4–94.4% of cells) or were able to synthesize and secrete L-DOPA (89.0–283 pmols/106 cells/h). After transduced rMSCs were plated at low density (3–6 cells/cm2), the cells expanded over 1000-fold in 3–4 weeks, and the rMSCs continued to either express GFP or produce L-DOPA. Furthermore, two high-expressing clones were isolated and expanded at low-density from rMSCs transduced with pSIR driven by the PGK promoter (97.0% GFP+ or 1096.0 pmols L-DOPA/106 cells/h).

MSCs derived from iPSCs with a modified protocol are tumor-tropic but have much less potential to promote tumors than bone marrow MSCs

Significance Mesenchymal stem or stromal cells (MSCs) offer great promise as potential therapies for cancers and other diseases. However, applications of MSCs for cancer therapy are hindered by their protumor potential under certain conditions, considerable donor variations, and limited expandability. Here we report generation of induced pluripotent stem cells (iPSC)-derived MSCs with same tumor homing capacity but much less protumor potential using a modified protocol with high derivation efficiency. Starting from iPSCs with almost unlimited expandability, the protocol can be readily scaled up to provide huge amounts of MSCs with uniform biological properties for multicenter evaluation, large animal experiments, and potential clinical trial. Moreover, therapeutic transgenes can be inserted into safe-harbor loci of iPSCs before derivation of MSCs to eliminate insertional mutation and guarantee stable expression of transgenes during prolonged expansion. Mesenchymal stem or stromal cells (MSCs) have many potential therapeutic applications including therapies for cancers and tissue damages caused by cancers or radical cancer treatments. However, tissue-derived MSCs such as bone marrow MSCs (BM-MSCs) may promote cancer progression and have considerable donor variations and limited expandability. These issues hinder the potential applications of MSCs, especially those in cancer patients. To circumvent these issues, we derived MSCs from transgene-free human induced pluripotent stem cells (iPSCs) efficiently with a modified protocol that eliminated the need of flow cytometric sorting. Our iPSC-derived MSCs were readily expandable, but still underwent senescence after prolonged culture and did not form teratomas. These iPSC-derived MSCs homed to cancers with efficiencies similar to BM-MSCs but were much less prone than BM-MSCs to promote the epithelial–mesenchymal transition, invasion, stemness, and growth of cancer cells. The observations were probably explained by the much lower expression of receptors for interleukin-1 and TGFβ, downstream protumor factors, and hyaluronan and its cofactor TSG6, which all contribute to the protumor effects of BM-MSCs. The data suggest that iPSC-derived MSCs prepared with the modified protocol are a safer and better alternative to BM-MSCs for therapeutic applications in cancer patients. The protocol is scalable and can be used to prepare the large number of cells required for “off-the-shelf” therapies and bioengineering applications.

Isolation and culture of bone marrow-derived human multipotent stromal cells (hMSCs).

We have developed protocols whereby a total of 30-90 x 10(6) hMSCs with an average viability greater than 90% can be produced in a single multilevel Cell Factory from a relatively small (1-3 mL) bone marrow aspirate in 14-20 d. It is possible to generate as many as 5 x 10(8) multipotent stromal cells (MSCs) from a single sample, depending on the number of Cell Factories seeded from the initial isolated hMSCs. Briefly, mononuclear cells are collected from a bone marrow aspirate by density gradient centrifugation. The cells are cultured overnight and the adherent cells are allowed to attach to the flask. Nonadherent cells are removed and the culture expanded for 7-10 d with periodic feeding of the cells. The cells are then harvested and seeded at low density (60-100 cells/cm2) into Nunc Cell Factories. The cells are allowed to expand for an additional 7-10 d, and are then harvested.

Novel object recognition in Apoe-/- mice improved by neonatal implantation of wild-type multipotential stromal cells

Multipotential bone marrow stromal cells (MSCs) from wild-type (Wt) or apolipoprotein E deficient (Apoe(-/-)) mice were implanted into the cerebral ventricles of Apoe(-/-) mice. MSCs from Wt mice continued expressing apoE up to 6 months after implantation and were associated with enhanced novel object recognition and increased microtubule-associated protein 2 (MAP2) immunoreactivity in the dentate gyrus. These data show that MSCs can be used to distinguish developmental from post-developmental effects of a gene knockout and support their therapeutic potential for neurodegenerative diseases.