Xenotransplantation of neonatal porcine bone marrow-derived mesenchymal stem cells improves murine hind limb ischemia through lymphangiogenesis and angiogenesis

Systematic review and meta-analysis of the effect of bone marrow-derived cell therapies on hind limb perfusion

Preclinical and clinical studies on the administration of bone marrow-derived cells to restore perfusion show conflicting results. We conducted a systematic review and meta-analysis on preclinical studies to assess the efficacy of bone marrow-derived cells in the hind limb ischemia model and identify possible determinants of therapeutic efficacy. In vivo animal studies were identified using a systematic search in PubMed and EMBASE on 10 January 2022. 85 studies were included for systematic review and meta-analysis. Study characteristics and outcome data on relative perfusion were extracted. The pooled mean difference was estimated using a random effects model. Risk of bias was assessed for all included studies. We found a significant increase in perfusion in the affected limb after administration of bone marrow-derived cells compared to that in the control groups. However, there was a high heterogeneity between studies, which could not be explained. There was a high degree of incomplete reporting across studies. We therefore conclude that the current quality of preclinical research is insufficient (low certainty level as per GRADE assessment) to identify specific factors that might improve human clinical trials.

Development and characterization of islet-derived mesenchymal stem cells from clinical grade neonatal porcine cryopreserved islets

BACKGROUND

Porcine tissues display a great potential as donor tissues in xenotransplantation, including cell therapy. Cryopreserving clinical grade porcine tissue and using it as a source for establishing therapeutic cells should be advantageous for transportation and scheduled manufacturing of MSCs. Of note, we previously performed encapsulated porcine islet transplantation for the treatment of unstable type 1 diabetes mellitus in the clinical setting. It has been reported that co-transplantation of islets and Mesenchymal stem cells (MSCs) enhanced efficacy. We assume that co-transplantation of porcine islets and porcine islet-derived MSCs could improve the efficacy of clinical islet xenotransplantation.

METHODS

MSCs were established from fresh and cryopreserved non-clinical grade neonatal porcine islets and bone marrow (termed non-clinical grade npISLET-MSCs and npBM-MSCs, respectively), as well as from cryopreserved clinical grade neonatal porcine islets (termed clinical grade npISLET-MSCs). Subsequently, the cell proliferation rate and diameter, surface marker expression, adipogenesis, osteogenesis, and colony-forming efficiency of the MSCs were assessed.

RESULTS

Cell proliferation rate and diameter did not differ between clinical grade and non-clinical grade npISLET-MSCs. However, non-clinical grade npBM-MSCs were significantly shorter and smaller than both npISLET-MSCs (p < 0.05). MSC markers (CD29, CD44, and CD90) were strongly expressed in clinical grade npISLET-MSCs and non-clinical grade npISLET-MSCs and npBM-MSCs. The expression of MSC-negative markers CD31, CD34, and SLA-DR was low in all MSCs. Clinical grade npISLET-MSCs derived from adipose and osteoid tissues were positive for Oil Red and alkaline phosphatase staining. The results of colony-forming assay were not significantly different between clinical grade npISLET-MSCs and non-clinical grade npBM-MSCs.

CONCLUSION

The method described herein was successful in of developing clinical grade npISLET-MSCs from cryopreserved islets. Cryopreserved clinical grade porcine islets could be an excellent stable source of MSCs for cell therapy.

Rescue of murine hind limb ischemia via angiogenesis and lymphangiogenesis promoted by cellular communication network factor 2

Critical limb ischemia (CLI) is caused by severe arterial blockage with reduction of blood flow. The aim of this study was to determine whether therapeutic angiogenesis using cellular communication network factor 2 (CCN2) would be useful for treating CLI in an animal model. Recombinant CCN2 was administered intramuscularly to male C57BL/6J mice with hind limb ischemia. The therapeutic effect was evaluated by monitoring blood flow in the ischemic hind limb. In an in vivo assay, CCN2 restored blood flow in the ischemic hind limb by promoting both angiogenesis and lymphangiogenesis. VEGF-A and VEGF-C expression levels increased in the ischemic limb after treatment with CCN2. In an in vitro assay, CCN2 promoted proliferation of vascular and lymphatic endothelial cells, and it upregulated expression of Tgfb1 followed by expression of Vegfc and Vegfr3 in lymphatic endothelial cells under hypoxia. Suppression of Tgfb1 did not affect the activity of CCN2, activation of the TGF-β/SMAD signaling pathway, or expression of Vegfr3 in lymphatic endothelial cells. In summary, treatment using recombinant CCN2 could be a promising therapeutic strategy for CLI.

Establishment of a Simple, Reproducible, and Long-lasting Hind Limb Animal Model of Lymphedema

Background

Lymphedema is an intractable disease for which there is currently no established curative therapy. A reliable and long-lasting lymphedema model is essential for development of better treatments. In this study, we aimed to establish a simple, reproducible and long-lasting mouse model of lymphedema.

Methods

Our model is characterized by a combination of a circumferential skin incision in the femoral region, complete dissection of regional lymph nodes, and ablation of the inguinal route in the femoral region. The characteristics of the lymphedema were evaluated and compared with those of two other models. One of these models involved dissection of the subiliac, popliteal, and sciatic lymph nodes (model A) and the other excision of the subiliac, popliteal, and sciatic lymph nodes with cauterization of lymphatic vessels and closure without a skin excision (model B).

Results

Although the lymphedema in models A and B resolved spontaneously, that in the new model lasted for a month with increases in femoral circumference and hind limb volume, thickening of the skin, especially subcutaneous tissue, and congestion of peripheral lymphatic vessels. Furthermore, this model could be used for assessing the therapeutic effects of syngeneic mesenchymal stem cell transplantation. The average operation time for the new model was 14.4 ± 1.3 minutes.

Conclusion

Long-lasting lymphedema can be achieved by our new model, making it suitable for assessing therapies for lymphedema.

Lymphangiogenesis, a potential treatment target for myocardial injury

The lymphatic vascular system is crucial for the regulation of tissue fluid homeostasis, lipid metabolism, and immune function. Cardiac injury quickly leads to myocardial edema, cardiac lymphatic dysfunction, which ultimately results in myocardial fluid imbalance and cardiac dysfunction. Therefore, lymphangiogenesis-targeted therapy may improve the recovery of myocardial function post cardiac ischemia as observed in myocardial infarction (MI). Indeed, a promising strategy for the clinical treatment of MI relies on vascular endothelial growth factor-C (VEGF-C)-targeted therapy, which promotes lymphangiogenesis. However, much effort is needed to identify the mechanisms of lymphatic transport in response to heart disease. This article reviews regulatory factors of lymphangiogenesis, and discusses the effects of lymphangiogenesis on cardiac function after cardiac injury and its regulatory mechanisms. The involvement of stem cells on lymphangiogenesis was also discussed as stem cells could differentiate into lymphatic endothelial cells (LECs) and stimulate phenotype of LECs.

The Impact of Stem/Progenitor Cells on Lymphangiogenesis in Vascular Disease

Lymphatic vessels, as the main tube network of fluid drainage and leukocyte transfer, are responsible for the maintenance of homeostasis and pathological repairment. Recently, by using genetic lineage tracing and single-cell RNA sequencing techniques, significant cognitive progress has been made about the impact of stem/progenitor cells during lymphangiogenesis. In the embryonic stage, the lymphatic network is primarily formed through self-proliferation and polarized-sprouting from the lymph sacs. However, the assembly of lymphatic stem/progenitor cells also guarantees the sustained growth of lymphvasculogenesis to obtain the entire function. In addition, there are abundant sources of stem/progenitor cells in postnatal tissues, including circulating progenitors, mesenchymal stem cells, and adipose tissue stem cells, which can directly differentiate into lymphatic endothelial cells and participate in lymphangiogenesis. Specifically, recent reports indicated a novel function of lymphangiogenesis in transplant arteriosclerosis and atherosclerosis. In the present review, we summarized the latest evidence about the diversity and incorporation of stem/progenitor cells in lymphatic vasculature during both the embryonic and postnatal stages, with emphasis on the impact of lymphangiogenesis in the development of vascular diseases to provide a rational guidance for future research.

Development and characterization of Gal KO porcine bone marrow-derived mesenchymal stem cells

BACKGROUND

We demonstrated that neonatal porcine bone marrow-derived mesenchymal stem cell (npBM-MSCs) could improve a critical ischemic limb disease in rat model more efficiently compared with human MSCs. However, since porcine MSC presents galactosyl-alpha 1,3-galactose antigen (Gal antigen), MSC could be eliminated by the xenogeneic rejection. Recently, we established Gal knockout (KO) pigs by a technique of the electroporation of the CRISPR/Cas9 system into vitro-fertilized zygotes. In this study, we hypothesized that MSC from the established Gal KO pigs could further improve the efficacy. Before examining the hypothesis, in this study, we have established and characterized bone marrow-derived MSC from the Gal KO adult pigs (apBM-MSCs).

METHODS

Mononuclear cells (MNCs) were isolated from bone marrow cells of both Gal KO adult pigs and wild-type (WT) adult pigs. MNCs were further manipulated to create Gal KO apBM-MSCs and WT apBM-MSCs. Both MSCs were assessed by their surface markers, the capability of differentiation into adipocytes, osteocytes and chondrocytes, grow speed and colony-forming assay. To assess the efficacy of Gal KO apBM-MSCs, angiogenesis-related genes and immunosuppression-related genes were assessed by cytokine stimulation.

RESULTS

Gal KO apBM-MSC showed no Gal antigen on their cell surfaces. Both Gal KO apBM-MSCs and WT apBM-MSCs, presented little or no negative surface markers of MSCs, while they presented positive surface markers of MSCs. Furthermore, Gal KO apBM-MSCs were able to differentiate into adipocytes, osteocytes, and chondrocytes as well as WT apBM-MSCs. There was no difference in doubling time between Gal KO apBM-MSCs and WT apBM-MSCs. Interestingly, the colony-forming efficiency of Gal KO apBM-MSCs was about half that of WT apBM-MSC. However, angiogenesis and immunosuppression-related genes were equally upregulated in both Gal KO apBM-MSCs and WT apBM-MSCs by cytokine stimulation.

CONCLUSION

We created and characterized Gal KO apBM-MSCs which showed similar characteristics and cytokine-induced gene upregulation to the WT apBM-MSCs.