Human endometrial perivascular stem cells exhibit a limited potential to regenerate endometrium after xenotransplantation.

STUDY QUESTION: What are the localization, characteristics and potential for tissue regeneration of two perivascular stem cells, namely CD34+ adventitial cells and CD146+ pericytes, in human endometrium? SUMMARY ANSWER: Human endometrial CD34+ adventitial cells (located in the outermost layer of blood vessels and mainly in the basal layer) and CD146+ pericytes showed mesenchymal stem cell (MSC) phenotypes in in vitro culture, but presented limited potential to regenerate endometrium. WHAT IS KNOWN ALREADY: Periodic endometrial regeneration is considered to be maintained by MSCs. Blood vessel wall, regarded as stem cell niche, harbors a large reserve of progenitor cells that may be integral to the origin of MSCs. However, a lack of validated markers has hampered the isolation of putative endometrial MSCs. Currently, CD146+ pericytes and Sushi Domain Containing 2 (SUSD2) positive cells have been identified in the endometrial perivascular region as sharing MSCs characteristics. STUDY DESIGN, SIZE, DURATION: The locations of adventitial cells and pericytes in the human endometrium were identified by immunofluorescence staining (n = 4). After CD34+CD146-CD45-CD56-CD144- adventitial cells and CD146+CD34-CD45-CD56-CD144- pericytes were isolated from the endometrium of normal women (n = 6) by fluorescence-activated cell sorting, their characteristics were investigated in culture. Adventitial cells and pericytes were induced to differentiate, respectively, into vascular endothelial-like cells or endometrial stromal-like cells in vitro, with their potential explored by in vivo xenotransplantation (n = 2 in each group) and eutopic transplantation (n = 2 in each group). PARTICIPANTS/MATERIALS, SETTING, METHODS: CD34+ adventitial cells and CD146+ pericytes were cultured in the inducing medium to differentiate into endothelial-like cells in vitro, and then analyzed for CD31, von Willebrand factor immunofluorescent staining and tube formation. They were also cultured to differentiate into endometrial stromal cells in vitro, with the expression of vimentin and CD13 being detected by western blot before and after induction, and the expression of prolactin and insulin-like growth factor-binding protein 1 being determined as well. Single dispersed CD34+ adventitial cells and CD146+ pericytes were respectively transplanted under the kidney capsule of NOG mice to investigate their differentiation potential in vivo. A eutopic transplantation model was constructed by grafting recellularized uterine matrix loaded up with CM-Dil labeled adventitial cells or pericytes into the injury region of nude rat's uterus. MAIN RESULTS AND THE ROLE OF CHANCE: CD34+ adventitial cells were mainly located at the outmost layer of endometrial large vessels, while CD146+ pericytes were found surrounding the inner endothelial cells of microvessels. A small proportion of CD34+ adventitial cells expressed SUSD2. The number of adventitial cells was ∼40 times higher than that of pericytes in the endometrium. Both adventitial cells and pericytes showed MSC phenotypes after in vitro culture. After in vitro induction into endometrial endothelial-like cells and stromal-like cells, adventitial cells showed higher plasticity than pericytes and a closer correlation with stromal-like cells. In the mouse xenotransplantation model, vimentin+ cells, CD31+ endothelial-like cells and CD146+ pericyte-like cells could be observed after adventitial cells were transplanted. CM-Dil-labeled adventitial cells or pericytes could survive in the immunocompromised nude rats after eutopic transplantation, and vimentin+ cells were detected. In addition, CM-Dil-labeled adventitial cells or pericytes did not express α-smooth muscle actin or E-cadherin after transplantation. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: CD34 was chosen as a novel marker to isolate adventitial cells from human endometrium according to previous literature. The association of endometrial CD34+ adventitial cells and SUSD2+ MSCs should be further investigated. WIDER IMPLICATIONS OF THE FINDINGS: The decellularized uterine matrix model might be useful in endometrial stem cell therapy. STUDY FUNDING/COMPETING INTEREST(S): L.D. is supported by grants from National Key Research and Development Program of China (2018YFC1004700), Nature Science Foundation of China (81871128, 81571391) and Nanjing Medical Science Development Project (ZKX16042). H.S. is supported by a grant from Jiangsu Province Social Development Project (BE2018602). X.Z. was supported by grants from the Postgraduate Innovative Project of Jiangsu Province (KYCX19-1177). The authors declare no conflict of interest.

Perivascular Stem Cells Suppress Inflammasome Activation during Inflammatory Responses in Macrophages.

BACKGROUND AND OBJECTIVES: Perivascular stem cells (PVCs) have been identified as precursors of mesenchymal stem cells (MSCs) that offer promising prospects for application in the development of cellular therapies. Although PVCs have been demonstrated to have greater therapeutic potential compared to bone marrow and adipose tissue-derived MSCs in various diseases, the regulatory role of PVCs on inflammasome activation during macrophage-mediated inflammatory responses has not been investigated. METHODS AND RESULTS: In this study, we found that the PVC secretome effectively alleviates secretion of both caspase-1 and interleukin-1ß in lipopolysaccharide-primed and activated human and murine macrophages by blocking inflammasome activation and attenuating the production of mitochondrial reactive oxygen species (ROS). We further showed that the PVC secretome significantly reduces inflammatory responses and endoplasmic reticulum stress in peritoneal macrophages in a mouse model of monosodium urate-induced peritonitis. A cytokine antibody array analysis revealed that the PVC secretome contains high levels of serpin E1 and angiogenin, which may be responsible for the inhibitory effects on mitochondrial ROS generation as well as on inflammasome activation. CONCLUSIONS: Our results suggest that PVCs may be therapeutically useful for the treatment of macrophage- and inflammation-mediated diseases by paracrine action via the secretion of various biological factors.

Perivascular Stem Cells Suppress Inflammasome Activation during Inflammatory Responses in Macrophages

BACKGROUND AND OBJECTIVES: Perivascular stem cells (PVCs) have been identified as precursors of mesenchymal stem cells (MSCs) that offer promising prospects for application in the development of cellular therapies. Although PVCs have been demonstrated to have greater therapeutic potential compared to bone marrow and adipose tissue-derived MSCs in various diseases, the regulatory role of PVCs on inflammasome activation during macrophage-mediated inflammatory responses has not been investigated.METHODS AND RESULTS: In this study, we found that the PVC secretome effectively alleviates secretion of both caspase-1 and interleukin-1β in lipopolysaccharide-primed and activated human and murine macrophages by blocking inflammasome activation and attenuating the production of mitochondrial reactive oxygen species (ROS). We further showed that the PVC secretome significantly reduces inflammatory responses and endoplasmic reticulum stress in peritoneal macrophages in a mouse model of monosodium urate-induced peritonitis. A cytokine antibody array analysis revealed that the PVC secretome contains high levels of serpin E1 and angiogenin, which may be responsible for the inhibitory effects on mitochondrial ROS generation as well as on inflammasome activation.CONCLUSIONS: Our results suggest that PVCs may be therapeutically useful for the treatment of macrophage- and inflammation-mediated diseases by paracrine action via the secretion of various biological factors.

Pericytes, an overlooked player in vascular pathobiology.

Pericytes are a heterogeneous population of cells located in the blood vessel wall. They were first identified in the 19th century by Rouget, however their biological role and potential for drug targeting have taken time to be recognised. Isolation of pericytes from several different tissues has allowed a better phenotypic and functional characterization. These findings revealed a tissue-specific, multi-functional group of cells with multilineage potential. Given this emerging evidence, pericytes have acquired specific roles in pathobiological events in vascular diseases. In this review article, we will provide a compelling overview of the main diseases in which pericytes are involved, from well-established mechanisms to the latest findings. Pericyte involvement in diabetes and cancer will be discussed extensively. In the last part of the article we will review therapeutic approaches for these diseases in light of the recently acquired knowledge. To unravel pericyte-related vascular pathobiological events is pivotal not only for more tailored treatments of disease but also to establish pericytes as a therapeutic tool.

Brief Report: Human Perivascular Stem Cells and Nel-Like Protein-1 Synergistically Enhance Spinal Fusion in Osteoporotic Rats.

Autologous bone grafts (ABGs) are considered as the gold standard for spinal fusion. However, osteoporotic patients are poor candidates for ABGs due to limited osteogenic stem cell numbers and function of the bone microenvironment. There is a need for stem cell-based spinal fusion of proven efficacy under either osteoporotic or nonosteoporotic conditions. The purpose of this study is to determine the efficacy of human perivascular stem cells (hPSCs), a population of mesenchymal stem cells isolated from adipose tissue, in the presence and absence of NELL-1, an osteogenic protein, for spinal fusion in the osteoporosis. Osteogenic differentiation of hPSCs with and without NELL-1 was tested in vitro. The results indicated that NELL-1 significantly increased the osteogenic potential of hPSCs in both osteoporotic and nonosteoporotic donors. Next, spinal fusion was performed by implanting scaffolds with regular or high doses of hPSCs, with or without NELL-1 in ovariectomized rats (n = 41). Regular doses of hPSCs or NELL-1 achieved the fusion rates of only 20%-37.5% by manual palpation. These regular doses had previously been shown to be effective in nonosteoporotic rat spinal fusion. Remarkably, the high dose of hPSCs+NELL-1 significantly improved the fusion rates among osteoporotic rats up to approximately 83.3%. Microcomputed tomography imaging and quantification further confirmed solid bony fusion with high dose hPSCs+NELL-1. Finally, histologically, direct in situ involvement of hPSCs in ossification was shown using undecalcified samples. To conclude, hPSCs combined with NELL-1 synergistically enhances spinal fusion in osteoporotic rats and has great potential as a novel therapeutic strategy for osteoporotic patients.