A Novel Immunodeficient Hyperglycemic Mouse Carrying the Ins1 Akita Mutation for Xenogeneic Islet Cell Transplantation.

BACKGROUND: For patients who have difficulty controlling blood glucose even with insulin administration, xenogeneic islet cells, including human stem cell-derived pancreatic islets (hSC-islet) and porcine islets, have garnered attention as potential solutions to challenges associated with donor shortages. For the development of diabetes treatment modalities that use cell transplantation therapy, it is essential to evaluate the efficacy and safety of transplanted cells using experimental animals over the long term. METHODS: We developed permanent diabetic immune-deficient mice by introducing the Akita (C96Y) mutation into the rodent-specific Insulin1 gene of NOD/Shi-scid IL2rγcnull (NOG) mice (Ins1C96Y/C96Y NOG). Their body weight, nonfasting blood glucose, and survival were measured from 4 wk of age. Insulin sensitivity was assessed via tolerance tests. To elucidate the utility of these mice in xenotransplantation experiments, we transplanted hSC-islet cells or porcine islets under the kidney capsules of these mice. RESULTS: All male and female homozygous mice exhibited persistent severe hyperglycemia associated with ß-cell depletion as early as 4 wk of age and exhibited normal insulin sensitivity. These mice could be stably engrafted with hSC-islets, and the mice that received porcine islet grafts promptly exhibited lowered blood glucose levels, maintaining blood glucose levels below the normal glucose range for at least 52 wk posttransplantation. CONCLUSIONS: The Ins1C96Y/C96Y NOG mouse model provides an effective platform to assess both the efficacy and safety of long-term xenograft engraftment without the interference of their immune responses. This study is expected to contribute essential basic information for the clinical application of islet cell transplantation.

The functional maturity of grafted human pluripotent stem cell derived-islets (hSC-Islets) evaluated by the glycemic set point during blood glucose normalizing process in diabetic mice.

Human pluripotent stem cell (hPSCs) derived-pancreatic islets (hSC-islets) are good candidates for cell replacement therapy for patients with diabetes as substitutes for deceased donor-derived islets, because they are pluripotent and have infinite proliferation potential. Grafted hSC-islets ameliorate hyperglycemia in diabetic mice; however, several weeks are needed to normalize the hyperglycemia. These data suggest hSC-islets require maturation, but their maturation process in vivo is not yet fully understood. In this study, we utilized two kinds of streptozotocin (STZ)-induced diabetes model mice by changing the administration timing in order to examine the time course of maturation of hSC-islets and the effects of hyperglycemia on their maturation. We found no hyperglycemia in immune-compromised mice when hSC-islets had been transplanted under their kidney capsules in advance, and STZ was administered 4 weeks after transplantation. Of note, the blood glucose levels of those mice were stably maintained under 100 mg/dl 10 weeks after transplantation; this is lower than the mouse glycemic set point (120-150 mg/dl), suggesting that hSC-islets control blood glucose levels to the human glycemic set point. We confirmed that gene expression of maturation markers of pancreatic beta cells tended to upregulate during 4 weeks after transplantation. Periodical histological analysis revealed that revascularization was observed as early as 1 week after transplantation, but reinnervation in the grafted hSC-islets was not detected at all, even 15 weeks after transplantation. In conclusion, our hSC-islets need at least 4 weeks to mature, and the human glycemic set point is a good index for evaluating ultimate maturity for hSC-islets in vivo.

Autologous angiogenic therapy with cultured mesenchymal stromal cells in platelet-rich plasma for critical limb ischemia.

Introduction: The prevalence of diabetes mellitus is increasing globally, including in Japan. Patients with diabetes often experience microangiopathy and macroangiopathy, which lead to difficult-to-treat foot ulcers and diabetic gangrene. Conventional cellular therapies have limited safety and are invasive. In this study, we investigated the use of cultured autologous mesenchymal stromal cells derived from the bone marrow and grown in platelet-rich plasma as a potential treatment for diabetic complications. Methods: A prospective clinical trial was conducted to assess safety as the primary endpoint and efficacy as the secondary endpoint of the aforementioned therapy in five patients with critical limb ischemia, with or without hemodialysis. Results: Five patients with critical limb ischemia were enrolled between 2016 and 2019, three of whom underwent hemodialysis. Platelet-rich plasma was obtained from 288 ± 39.6 mL of blood/patient, yielding 31.6 ± 1.67 mL of platelet-rich plasma. Bone marrow aspiration yielded 18.4 ± 4.77 mL/patient, and 4.64 ± 1.51 × 107 cells were incubated for 16 ± 2.8 days to obtain 3.26 ± 0.33 × 107 mesenchymal stromal cells. Although several adverse events were observed, none were directly attributed to cell therapy. Clinical severity, as assessed by both the Fontaine stage and Rutherford category, improved significantly following therapy. This improvement was accompanied by enhancements in the 6-min walking distance, dorsal skin perfusion pressure, ankle transcutaneous partial oxygen pressure, and ankle brachial pressure index. Conclusion: Autologous angiogenic therapy with cultured mesenchymal stromal cells derived from the bone marrow and grown in platelet-rich plasma is a safe and feasible, and was expected as a potential treatment for critical limb ischemia.

TERT/BMI1-transgenic human dermal papilla cells enhance murine hair follicle formation in vivo.

BACKGROUND: Dermal papilla cells (DPCs) are one type of mesenchymal cells; they play a key role on hair follicle induction. Their hair inductivity and proliferation abilities are rapidly lost during the 2-dimensional culture. Cell senescence is induced by inadequate culture conditions and telomere shortening. We previously reported that overexpression of TERT coding telomerase reverse transcriptase and BMI1 coding human B-cell-specific Moloney murine leukemia virus insertion region 1 (BMI1) avoided senescence of murine DPC and restored hair inductive activity. OBJECTIVE: To evaluate the function of TERT and BMI1 in the human DPCs (hDPCs). METHODS: Cultured hDPCs obtained from human scalp hair were transduced with TERT alone (hDP-T), BMI1 alone (hDP-B), both TERT and BMI1 (hDP-TB) and empty vector (hDP-E). The hair inductive activity of those cells was assessed by chamber assay in vivo. Gene expressions were analyzed by quantitative PCR (q-PCR). RESULTS: hDP-TB proliferated more than hDP-T and hDP-B in vitro and only hDP-TB showed hair inductivity in vivo. Moreover, the expressions of VCAN, CTNNB1, LEF1, FGF7 and VEGFA in hDP-TB were elevated compared to those in hDP-E. CONCLUSION: Overexpression of both TERT and BMI1 extends the life span of cultured hDPCs and ameliorates their hair inducing ability on mouse hair follicles.

Lymphatic Dysfunction Exacerbates Cutaneous Tumorigenesis and Psoriasis-Like Skin Inflammation through Accumulation of Inflammatory Cytokines.

Lymphatic transport plays an important role in coordinating local immune responses. However, the biologic effects of impaired lymphatic flow in vivo are not fully understood. In this study, we investigated the roles of the lymphatic system in skin carcinogenesis and psoriasis-like inflammation using k-cyclin transgenic (kCYC+/-) mice, which demonstrate severe lymphatic dysfunction. kCYC+/- mice showed augmented tumor growth in the two-stage skin carcinogenesis model and severe clinical scores in imiquimod-induced psoriasis-like skin inflammation compared with wild-type mice. Although mRNA levels of inflammatory cytokines in skin after topical application of 12-O-tetradecanoylphorbol-13-acetate or imiquimod were comparable between kCYC+/- and wild-type mice, protein levels of inflammatory cytokines, such as IL-17A, IL-22, and IL-23, were significantly upregulated in kCYC+/- mice in both models. Consistently, signal transducer and activator of transcription 3 pathway and NF-κB signaling were augmented in epidermal keratinocytes in kCYC+/- mice. These results suggest that lymphatic dysfunction in kCYC+/- mice caused accumulation of inflammatory cytokines, leading to the exacerbation of two-stage skin carcinogenesis and imiquimod-induced psoriasis-like skin inflammation. These findings add insight into the clinical problems of secondary malignancies and inflammatory dermatoses that may occur with extremity lymphedema.

Lotus-root-shaped cell-encapsulated construct as a retrieval graft for long-term transplantation of human iPSC-derived ß-cells.

Cell therapy using human-stem-cell-derived pancreatic beta cells (hSC-ßs) is a potential treatment method for type 1 diabetes mellitus (T1D). For therapeutic safety, hSC-ßs need encapsulation in grafts that are scalable and retrievable. In this study, we developed a lotus-root-shaped cell-encapsulated construct (LENCON) as a graft that can be retrieved after long-term hSC-ß transplantation. This graft had six multicores encapsulating hSC-ßs located within 1 mm from the edge. It controlled the recipient blood glucose levels for a long-term, following transplantation in immunodeficient diabetic mice. LENCON xenotransplanted into immunocompetent mice exhibited retrievability and maintained the functionality of hSC-ßs for over 1 year after transplantation. We believe that LENCON can contribute to the treatment of T1D through long-term transplantation of hSC-ßs and in many other forms of cell therapy.

Efficient induction of pancreatic alpha cells from human induced pluripotent stem cells by controlling the timing for BMP antagonism and activation of retinoic acid signaling.

Diabetes mellitus is caused by breakdown of blood glucose homeostasis, which is maintained by an exquisite balance between insulin and glucagon produced respectively by pancreatic beta cells and alpha cells. However, little is known about the mechanism of inducing glucagon secretion from human alpha cells. Many methods for generating pancreatic beta cells from human pluripotent stem cells (hPSCs) have been reported, but only two papers have reported generation of pancreatic alpha cells from hPSCs. Because NKX6.1 has been suggested as a very important gene for determining cell fate between pancreatic beta and alpha cells, we searched for the factors affecting expression of NKX6.1 in our beta cell differentiation protocols. We found that BMP antagonism and activation of retinoic acid signaling at stage 2 (from definitive endoderm to primitive gut tube) effectively suppressed NKX6.1 expression at later stages. Using two different hPSCs lines, treatment with BMP signaling inhibitor (LDN193189) and retinoic acid agonist (EC23) at Stage 2 reduced NKX6.1 expression and allowed differentiation of almost all cells into pancreatic alpha cells in vivo after transplantation under a kidney capsule. Our study demonstrated that the cell fate of pancreatic cells can be controlled by adjusting the expression level of NKX6.1 with proper timing of BMP antagonism and activation of retinoic acid signaling during the pancreatic differentiation process. Our method is useful for efficient induction of pancreatic alpha cells from hPSCs.

New Role for Growth/Differentiation Factor 15 in the Survival of Transplanted Brown Adipose Tissues in Cooperation with Interleukin-6.

To identify factors involved in the earliest phase of the differentiation of human embryonic stem cells (hESCs) into brown adipocytes (BAs), we performed multi-time point microarray analyses. We found that growth/differentiation factor 15 (GDF15) expressions were specifically upregulated within three days of differentiation, when expressions of immature hESC markers were sustained. Although GDF15 expressions continued to increase in the subsequent differentiation phases, GDF15-deficient hESCs differentiated into mature BAs (Day 10) without apparent abnormalities. In addition, GDF15-deficient mice had normal brown adipose tissue (BAT) and were metabolically healthy. Unexpectedly, we found that interleukin-6 (IL6) expression was significantly lowered in the BAT of GDF15-/- mice. In addition, GDF15-/- hESCs showed abortive IL6 expressions in the later phase (>Day 6) of the differentiation. Interestingly, GDF15 expression was markedly repressed throughout the whole course of the differentiation of IL6-/- hESCs into BAs, indicating IL6 is essential for the induction of GDF15 in the differentiation of hESCs. Finally, intraperitoneally transplanted BAT grafts of GDF15-/- donor mice, but not those of wild-type (WT) mice, failed in the long-term survival (12 weeks) in GDF15-/- recipient mice. Collectively, GDF15 is required for long-term survival of BAT grafts by creating a mutual gene induction loop with IL6.

Abnormal keratinization and cutaneous inflammation in Mal de Meleda.

Mal de Meleda (MDM) is a rare, autosomal recessive form of palmoplantar keratoderma due to mutations in the gene, encoding for secreted lymphocyte antigen 6/urokinase-type plasminogen activator receptor related protein 1 (SLURP1). We report a four-year-old Taiwanese MDM female case whose biopsy specimen of hyperkeratotic lesions showed abnormal keratinization and cutaneous inflammation with characteristic transmission electron microscopic (TEM) findings and immunostaining results. The patient presented with pruritic and severely hyperkeratotic plaques on the bilateral palms and soles whichwere fringed with erythematous scaly areas. A homozygous c.256 G>A mutation, predicting a conversion of p.Gly86Arg, in SLURP1gene was detected. Histopathological examinations showed marked hyperkeratosis, acanthosis and hypergranulosis in the epidermis, accompanied by perivascular lymphocytic infiltrates in the dermis. The whole layers of the epidermis and perivascular infiltrates of the dermis were stained positive with anti-tumor necrosis factor alpha (TNFα) antibody in the biopsy specimen from the sole and the ankle. TEM examination of the biopsy specimen from the plantar hyperkeratotic plaque showed various-sized vacuoles surrounding nuclei of many keratinocytes in the spinous layer. In addition, there were numerous irregular keratohyaline granules in the granular layer. Several microorganisms and many lipid-like droplets were found in the thickened cornified layer. SLURP1 protein is known as a marker of late differentiation, predominantly expressed in the granular layer, and also known to have an inhibitory effect on TNFα release. Our results exhibited excessive TNFα expression in keratinocytes and perivascular infiltrates of the dermis, and several characteristic morphological observations of keratinocytes in MDM.

The intraperitoneal space is more favorable than the subcutaneous one for transplanting alginate fiber containing iPS-derived islet-like cells.

INTRODUCTION: Although immunosuppressants are required for current islet transplantation for type 1 diabetic patients, many papers have already reported encapsulation devices for islets to avoid immunological attack. The aim of this study is to determine the optimal number of cells and optimal transplantation site for human iPS-derived islet-like cells encapsulated in alginate fiber using diabetic model mice. METHODS: We used a suspension culture system for inducing islet-like cells from human iPS cells throughout the islet differentiation process. Islet-like spheroids were encapsulated in the alginate fiber, and cell transplantation experiments were performed with STZ-induced diabetic NOD/SCID mice. We compared the efficacy of transplanted cells between intraperitoneal and subcutaneous administration of alginate fibers by measuring blood glucose and human C-peptide levels serially in mice. Grafts were analyzed histologically, and gene expression in pancreatic ß cells was also compared. RESULTS: We demonstrated the reversal of hyperglycemia in diabetic model mice after intraperitoneal administration of these fibers, but not with subcutaneous ones. Intraperitoneal fibers were easily retrieved without any adhesion. Although we detected human c-peptide in mice plasma after subcutaneous administration of these fibers, these fibers became encased by fibrous tissue. CONCLUSIONS: These results suggest that the intraperitoneal space is favorable for islet-like cells derived from human iPS cells when encapsulated in alginate fiber.

Induction of functional islet-like cells from human iPS cells by suspension culture.

INTRODUCTION: To complement islet transplantation for type1 diabetic patients, cell-based therapy using pluripotent stem cells such as ES cells and iPS cells is promising. Many papers have already reported the induction of pancreatic ß cells from these cell types, but a suspension culture system has not usually been employed. The aim of this study is to establish a suspension culture method for inducing functional islet-like cells from human iPS cells. METHODS: We used 30 ml spinner type culture vessels for human iPS cells throughout the differentiation process. Differentiated cells were analyzed by immunostaining and C-peptide secretion. Cell transplantation experiments were performed with STZ-induced diabetic NOD/SCID mice. Blood human C-peptide and glucagon levels were measured serially in mice, and grafts were analyzed histologically. RESULTS: We obtained spherical pancreatic beta-like cells from human iPS cells and detected verifiable amounts of C-peptide secretion in vitro. We demonstrated reversal of hyperglycemia in diabetic model mice after transplantation of these cells, maintaining non-fasting blood glucose levels along with the human glycemic set point. We confirmed the secretion of human insulin and glucagon dependent on the blood glucose level in vivo. Immunohistological analysis revealed that grafted cells became α, ß and δ cells in vivo. CONCLUSIONS: These results suggest that differentiated cells derived from human iPS cells grown in suspension culture mature and function like pancreatic islets in vivo.

Endodermal differentiation of human induced pluripotent stem cells using simple dialysis culture system in suspension culture.

A differentiation of human induced pluripotent stem cells (hiPSCs) into definitive endoderm linage is required for a preparation of metabolic organ derived cells. The differentiation consumed high-priced cytokines and small molecules, which have hampered the manufacturability of differentiated cells. Although the cytokines and small molecules are remained or cells produce the autocrine factors, daily culture medium change should be proceeded to remove toxic metabolites generated from cells. In this study, we developed a simple dialysis culture system to refine the medium during definitive endodermal differentiation. We demonstrated that dialysis culture prevented cell damage to remove lactate. The hiPSCs cultured with dialysis also differentiated similarly as usual differentiation without dialysis even if they were not supplied Activin A for latter culture days in the differentiation. With this dialysis culture system, hiPSCs were differentiated into endodermal lineage with medium refinement and recycling and autocrine factors as well as cytokines, which may lead to reduce differentiation cost.

Characterization of Peribiliary Gland-Constituting Cells Based on Differential Expression of Trophoblast Cell Surface Protein 2 in Biliary Tract.

Peribiliary glands (PBGs) are accessory glands with mucinous and serous acini in the biliary tree. The PBG is composed of a heterogeneous cell population, such as mucus- and pancreatic enzyme-producing epithelial cells, whereas it constitutes niches for multipotential stem/progenitor cells in the human extrahepatic bile duct (EHBD). By contrast, the nature of PBGs in the mouse EHBD remains unclear. Our aim was to establish a method for isolating and characterizing PBG-constituting cells in the mouse EHBD. We found that trophoblast cell surface protein 2 (Trop2) was expressed in the luminal epithelium of mouse EHBD exclusively, but not in the PBG. On the basis of the differential expression profile of Trop2, lumen-forming biliary epithelial cells (LBECs) and PBG-constituting epithelial cells (PBECs) were separately isolated for further characterization. Gene expression analysis revealed that the isolated mouse PBECs expressed several marker genes related to human PBGs. In the colony formation assay, PBECs showed significantly higher colony formation capacity than LBECs. In the organoid formation assay, PBECs formed cystic organoid with LBEC-like phenotype. Interestingly, PBECs proliferated, accompanied by reexpression of Trop2 in vivo after bile duct ligation. Furthermore, the unique expression profile of Trop2 was conserved in human EHBD. Our findings indicate that Trop2 is a useful marker in investigating the pathophysiological roles and characteristics of mouse and human PBGs in biliary diseases.

Differential expression of Lutheran/BCAM regulates biliary tissue remodeling in ductular reaction during liver regeneration.

Under chronic or severe liver injury, liver progenitor cells (LPCs) of biliary origin are known to expand and contribute to the regeneration of hepatocytes and cholangiocytes. This regeneration process is called ductular reaction (DR), which is accompanied by dynamic remodeling of biliary tissue. Although the DR shows apparently distinct mode of biliary extension depending on the type of liver injury, the key regulatory mechanism remains poorly understood. Here, we show that Lutheran (Lu)/Basal cell adhesion molecule (BCAM) regulates the morphogenesis of DR depending on liver disease models. Lu+ and Lu- biliary cells isolated from injured liver exhibit opposite phenotypes in cell motility and duct formation capacities in vitro. By overexpression of Lu, Lu- biliary cells acquire the phenotype of Lu+ biliary cells. Lu-deficient mice showed severe defects in DR. Our findings reveal a critical role of Lu in the control of phenotypic heterogeneity of DR in distinct liver disease models.

Efficient generation of functional pancreatic ß-cells from human induced pluripotent stem cells.

BACKGROUND: Insulin-secreting cells have been generated from human embryonic or induced pluripotent stem cells (iPSCs) by mimicking developmental processes. However, these cells do not always secrete glucose-responsive insulin, one of the most important characteristics of pancreatic ß-cells. We focused on the importance of endodermal differentiation from human iPSCs in order to obtain functional pancreatic ß-cells. METHODS: A six-stage protocol was established for the differentiation of human iPSCs to pancreatic ß-cells using defined culture media without feeders or serum. The effects of CHIR99021, a selective glycogen synthase kinase-3ß inhibitor, were examined in the presence of fibroblast growth factor 2, activin, and bone morphogenetic protein 4 (FAB) during definitive endodermal induction by immunostaining for SRY (sex determining region Y)-box 17 (SOX17) and Forkhead box protein A2 (FOXA2). Insulin secretion was compared between the last stage of monolayer culture and spheroid culture conditions. Cultured cells were transplanted under kidney capsules of streptozotocin-diabetic non-obese diabetic-severe combined immunodeficiency mice, and blood glucose levels were measured once a week. Immunohistochemical analyses were performed 4 and 12 weeks after transplantation. RESULTS: Addition of CHIR99021 (3 µmol/L) in the presence of FAB for 2 days improved endodermal cell viability, maintaining the high SOX17-positive rate. Spheroid formation after the endocrine progenitor stage showed more efficient insulin secretion than did monolayer culture. After cell transplantation, diabetic mice had lower blood glucose levels, and islet-like structures were detected in vivo. CONCLUSION: Functional pancreatic ß-cells were generated from human iPSCs. Induction of definitive endoderm and spheroid formation may be key steps for producing these cells.

Decreased interleukin-21 expression in skin and blood in advanced mycosis fungoides.

Interleukin (IL)-21 is regarded as a potent antitumor agent, which increases the cytotoxicity of both natural killer (NK) and CD8(+) T cells. In this study, we investigated the role of IL-21 in mycosis fungoides (MF). IL-21 mRNA expression levels in patch and plaque MF were significantly higher than those in normal skin. IL-21 mRNA expression levels in tumor MF were significantly decreased compared with those in patch and plaque MF. Interestingly, mRNA expression levels of IL-21 in MF lesional skin significantly correlated with those of T-helper type-1 cytokines/chemokines such as CXCL10, CXCL11 and γ-interferon. Immunohistochemistry showed that IL-21 was expressed by keratinocytes in patch and plaque MF. Furthermore, serum IL-21 levels in patients with tumor MF were significantly lower than those of healthy controls and plaque MF. Thus, IL-21 expression was significantly downregulated in skin and blood of patients with tumor MF, which may contribute to progression of MF. Our study suggests that recombinant IL-21 would be a promising therapy for MF.

Lymphatic dysfunction attenuates tumor immunity through impaired antigen presentation.

Tumor growth and metastasis of cancer involve autonomous tumor cell growth and host-tumor interactions. While tumor-specific immunity has been intensively studied in vitro, dynamic roles of lymphatic transport on tumor immunity in vivo have not been fully elucidated. In this study, we examined tumor growth and anti-tumor immune responses using kCYC mice, which demonstrate severe lymphatic dysfunction. Primary tumor growth was augmented in kCYC mice (compared to wild-type mice) when B16 melanoma or EL-4 lymphoma cells were subcutaneously injected. Expression of inflammatory cytokines such as IFN-γ, TNF-α, and IL-2 as well as IL-10 expression in draining lymph nodes (LNs) was significantly reduced in kCYC mice after tumor inoculation. Moreover, decreased levels of tumor-associated antigens were detected in draining LNs in kCYC mice, together with impaired antigen presentation. CD8+ T cells in draining LNs derived from kCYC mice bearing B16 melanoma also showed significantly decreased cytotoxic activity in vitro. Finally, tumor suppression activity of CD8+ T cells derived from kCYC mice bearing B16 melanoma was reduced when adoptively transferred to naive wild-type mice. In summary, these findings suggest that lymphatic transport is essential in generating optimal tumor-specific immune responses mediated by CD8+ T cells.

Case series of patients with chronic foot ulcers treated with autologous platelet-rich plasma.

Treatment for patients with chronic wounds is entering a new era, and autologous platelet-rich plasma (PRP) is among the most promising treatments. PRP contains a concentration of platelets obtained by centrifuging the patient's blood. Because it contains fibrin and high concentrations of growth factors, PRP is known to promote wound healing. In this study, we present five patients with chronic foot ulcers successfully treated with PRP in our institution. The patients had various underlying diseases: diabetes (n = 2), peripheral arterial disease (n = 1), both diabetes and peripheral arterial disease (n = 1), and cutaneous polyarteritis nodosa (n = 1). Also, we provide a description of PRP's mechanisms, advantages, and limitations.

Safety assessment of bone marrow derived MSC grown in platelet-rich plasma.

The injection of endothelial progenitor cells and mononuclear cells derived from bone marrow at the ischemic region of peripheral artery disease patients is reported to be effective for therapeutic angiogenesis; however, these cell therapies require large amounts of bone marrow to obtain sufficient numbers of cells. To solve this problem, we attempted to culture bone-marrow-derived mesenchymal stem cells (BM-MSC), which are supposed to secrete several cytokines that promote angiogenesis. We also focused on using platelet-rich plasma (PRP) as a supplement for cell culture instead of fetal bovine serum. Human BM-MSC obtained from healthy volunteers expanded rapidly when cultured with 10% PRP prepared from their own blood. FACS analysis revealed that these cultured human MSC were homogeneous populations, and chromosomal analysis showed a normal karyotype. Moreover, the angiogenetic effect was apparent two weeks after human BM-MSC were injected into the ischemic muscle in SCID mice. Tumor formation was not detected three months after injection into SCID mice either subcutaneously or intramuscularly. To simulate clinical settings, canine BM-MSC were grown with canine PRP and injected into their ischemic muscles. We confirmed that donor cells existed in situ two and six weeks after operation without any side effects. These results suggest that cultured human BM-MSC can be a promising cell source for therapeutic angiogenesis.

Delayed wound healing due to increased interleukin-10 expression in mice with lymphatic dysfunction.

Skin wound healing is an interactive process involving soluble mediators, ECM, resident cells, and infiltrating cells. Little is known about wound healing in the presence of lymphedema. In this study, we investigated wound healing using kCYC⁺/⁻ mice, which demonstrate severe lymphatic dysfunction. Wound healing was delayed significantly in kCYC⁺/⁻ mice when compared with WT mice. In wounded skin of kCYC⁺/⁻ mice, mast cell numbers were increased compared with WT mice, whereas macrophage numbers were decreased. Moreover, IL-10 expression by mast cells was increased, and expression of bFGF, mainly produced by macrophages, was decreased in wounded skin of kCYC⁺/⁻ mice compared with WT mice. We next crossed kCYC⁺/⁻ mice with IL-10⁻/⁻ mice, which were reported to show accelerated wound closure. In kCYC⁺/⁻ IL-10⁺/⁻ mice, time course of wound healing, numbers of macrophages, and IL-10 mRNA expression levels in wounded skin were comparable with WT IL-10⁺/⁻ mice. Similar results were obtained using a different lymphedema model, in which circumferential skin excision was performed on the tails of mice to remove the superficial lymphatics. In summary, these findings suggest that IL-10 plays an important role in delayed wound healing in the setting of lymphatic dysfunction.