Shuyang He

Human placenta-derived adherent cells prevent bone loss, stimulate bone formation, and suppress growth of multiple myeloma in bone.

Human placenta has emerged as a valuable source of transplantable cells of mesenchymal and hematopoietic origin for multiple cytotherapeutic purposes, including enhanced engraftment of hematopoietic stem cells, modulation of inflammation, bone repair, and cancer. Placenta‐derived adherent cells (PDACs) are mesenchymal‐like stem cells isolated from postpartum human placenta. Multiple myeloma is closely associated with induction of bone disease and large lytic lesions, which are often not repaired and are usually the sites of relapses. We evaluated the antimyeloma therapeutic potential, in vivo survival, and trafficking of PDACs in the severe combined immunodeficiency (SCID)–rab model of medullary myeloma‐associated bone loss. Intrabone injection of PDACs into nonmyelomatous and myelomatous implanted bone in SCID‐rab mice promoted bone formation by stimulating endogenous osteoblastogenesis, and most PDACs disappeared from bone within 4 weeks. PDACs inhibitory effects on myeloma bone disease and tumor growth were dose‐dependent and comparable with those of fetal human mesenchymal stem cells (MSCs). Intrabone, but not subcutaneous, engraftment of PDACs inhibited bone disease and tumor growth in SCID‐rab mice. Intratumor injection of PDACs had no effect on subcutaneous growth of myeloma cells. A small number of intravenously injected PDACs trafficked into myelomatous bone. Myeloma cell growth rate in vitro was lower in coculture with PDACs than with MSCs from human fetal bone or myeloma patients. PDACs also promoted apoptosis in osteoclast precursors and inhibited their differentiation. This study suggests that altering the bone marrow microenvironment with PDAC cytotherapy attenuates growth of myeloma and that PDAC cytotherapy is a promising therapeutic approach for myeloma osteolysis. STEM CELLS 2011;29:263–273

Human placenta-derived adherent cells induce tolerogenic immune responses

Human placenta‐derived adherent cells (PDAC cells) are a culture expanded, undifferentiated mesenchymal‐like population derived from full‐term placental tissue, with immunomodulatory and anti‐inflammatory properties. PDA‐001 (cenplacel‐L), an intravenous formulation of PDAC cells, is in clinical development for the treatment of autoimmune and inflammatory diseases. To elucidate the mechanisms underlying the immunoregulatory properties of PDAC cells, we investigated their effects on immune cell populations, including T cells and dendritic cells (DC) in vitro and in vivo. PDAC cells suppressed T‐cell proliferation in an OT‐II T‐cell adoptive transfer model, reduced the severity of myelin oligodendrocyte glycoprotein peptide‐induced experimental autoimmune encephalomyelitis and ameliorated inflammation in a delayed type hypersensitivity response model. In vitro, PDAC cells suppressed T‐cell proliferation and inhibited Th1 and Th17 differentiation. Analysis of tissues derived from PDAC cell‐treated animals revealed diminished CD86 expression on splenic DC, suggesting that they can also modulate DC populations. Furthermore, PDAC cells modulate the differentiation and maturation of mouse bone marrow‐derived DC. Similarly, human DC differentiated from CD14+ monocytes in the presence of PDAC cells acquired a tolerogenic phenotype. These tolerogenic DC failed to induce allogeneic T‐cell proliferation and differentiation toward Th1, but skewed T‐cell differentiation toward Th2. Inhibition of cyclo‐oxygenase‐2 activity resulted in a significant, but not complete, abrogation of PDAC cells’ effects on DC phenotype and function, implying a role for prostaglandin E2 in PDAC‐mediated immunomodulation. This study identifies modulation of DC differentiation toward immune tolerance as a key mechanism underlying the immunomodulatory activities of PDAC cells.

Human placenta-derived adherent cell treatment of experimental stroke promotes functional recovery after stroke in young adult and older rats.

Background Human Placenta-Derived Adherent Cells (PDAC®) are a novel mesenchymal-like cell population derived from normal human placental tissue. PDA-001 is a clinical formulation of PDAC® developed for intravenous administration. In this study, we investigated the efficacy of PDA-001 treatment in a rat model of transient middle cerebral artery occlusion (MCAo) in young adult (2–3 month old) and older rats (10–12 months old). Methods To evaluate efficacy and determine the optimal number of transplanted cells, young adult Wistar rats were subjected to MCAo and treated 1 day post MCAo with 1×106, 4×106 or 8×106 PDA-001 cells (i.v.), vehicle or cell control. 4×106 or 8×106 PDA-001 cells were also tested in older rats after MCAo. Treatment response was evaluated using a battery of functional outcome tests, consisting of adhesive-removal test, modified Neurological Severity Score (mNSS) and foot-fault test. Young adult rats were sacrificed 56 days after MCAo, older rats were sacrificed 29 days after MCAo, and lesion volumes were measured using H&E. Immunohistochemical stainings for bromodeoxyuridine (BrdU) and von Willebrand Factor (vWF), and synaptophysin were performed. Results In young adult rats, treatment with 4×106 PDA-001 cells significantly improved functional outcome after stroke (p<0.05). In older rats, significant functional improvement was observed with PDA-001 cell therapy in both of the 4×106 and 8×106 treatment groups. Functional benefits in young adult and older rats were associated with significant increases in the number of BrdU immunoreactive endothelial cells, vascular density and perimeter in the ischemic brain, as well as significantly increased synaptophysin expression in the ischemic border zone (p<0.05). Conclusion PDA-001 treatment significantly improved functional outcome after stroke in both young adult and older rats. The neurorestorative effects induced by PDA-001 treatment may be related to increased vascular density and synaptic plasticity.

Placenta-derived adherent cells attenuate hyperalgesia and neuroinflammatory response associated with perineural inflammation in rats.

Neuropathic pain is a debilitating condition of the somatosensory system caused by pathology of the nervous system. Current drugs treat symptoms but largely fail to target the underlying mechanisms responsible for the pathological changes seen in the central or peripheral nervous system. We investigated the therapeutic effects of PDA-001, a culture expanded placenta-derived adherent cell, in the rat neuritis model. Pain is induced in the model by applying carrageenan to the sciatic nerve trunk, causing perineural inflammation of the sciatic nerve. PDA-001, at doses ranging from 0.4×10(6) to 4×10(6) cells/animal, or vehicle control was intravenously administrated to assess the biological activity of the cells. A dose-dependent effect of PDA-001 on pain relief was demonstrated. PDA-001 at doses of 1×10(6) and 4×10(6), but not 0.4×10(6), reduced mechanical hyperalgesia within 24h following treatment and through day 8 after induction of neuritis. The mechanism underlying PDA-001-mediated reduction of neuroinflammatory pain was also explored. Ex vivo tissue analyses demonstrated that PDA-001 suppressed homing, maturation and differentiation of dendritic cells, thus inhibiting T-cell priming and activation in draining lymph nodes. PDA-001 also reduced interferon gamma and IL-17 in draining lymph nodes and in the ispilateral sciatic nerve, and increased the levels of IL-10 in draining lymph nodes and plasma, pointing to T-cell modulation as a possible mechanism mediating the observed anti-hyperalgesic effects. Furthermore, in the ipsilateral sciatic nerve, significantly less leukocyte infiltration was observed in PDA-001-treated animals. The results suggest that PDA-001may provide a novel therapeutic approach in the management of inflammatory neuropathic pain and similar conditions.

Human Placenta‐Derived Mesenchymal Stromal‐Like Cells Enhance Angiogenesis via T Cell‐Dependent Reprogramming of Macrophage Differentiation

Peripheral arterial disease (PAD) is a leading cause of limb loss and mortality worldwide with limited treatment options. Mesenchymal stromal cell (MSC) therapy has demonstrated positive effects on angiogenesis in preclinical models and promising therapeutic efficacy signals in early stage clinical studies; however, the mechanisms underlying MSC‐mediated angiogenesis remain largely undefined. Here, we investigated the mechanism of action of human placenta‐derived MSC‐like cells (PDA‐002) in inducing angiogenesis using mice hind limb ischemia model. We showed that PDA‐002 improved blood flow and promoted collateral vessel formation in the injured limb. Histological analysis demonstrated that PDA‐002 increased M2‐like macrophages in ischemic tissue. Analysis of the changes in functional T cell phenotype in the draining lymph nodes revealed that PDA‐002 treatment was associated with the induction of cytokine and gene expression signatures of Th2 response. Angiogenic effect of PDA‐002 was markedly reduced in Balb/c nude mice compared with wild type. This reduction in efficacy was reversed by T cell reconstitution, suggesting T cells are essential for PDA‐002‐mediated angiogenesis. Furthermore, effect of PDA‐002 on macrophage differentiation was also T cell‐dependent as a PDA‐002‐mediated M2‐like macrophage skewing was only observed in wild type and T cell reconstituted nude mice, but not in nude mice. Finally, we showed that PDA‐002‐treated animals had enhanced angiogenic recovery in response to the second injury when PDA‐002 no longer persisted in vivo. These results suggest that PDA‐002 enhances angiogenesis through an immunomodulatory mechanism involving T cell‐dependent reprogramming of macrophage differentiation toward M2‐like phenotype. Stem Cells 2017;35:1603–1613