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Abstract Background Critical limb ischemia (CLI) is a condition characterized by insufficient blood flow to the lower limbs, resulting in severe ischemia and potentially leading to amputation. This study aims to identify novel vasculogenic precursor cells (VPCs) in human bone marrow and evaluate their efficacy in combination with bone marrow-derived mesenchymal stem cells (BM-MSCs) for the treatment of CLI. Methods Ex vivo cultured VPCs and BM-MSCs from bone marrow were characterized and their effects on neovascularization and long-term tissue regeneration were tested in a mouse CLI model. Results VPCs, expressing high levels of hepatocyte growth factor and c-MET, were identified from human bone marrow aspirates. These cells exhibited strong vasculogenic capacity in vitro but possessed a cellular phenotype distinct from those of previously reported endothelial precursor cells in circulation or cord blood. They also expressed most surface markers of BM-MSCs and demonstrated multipotent differentiation ability. Screening of 376 surface markers revealed that VPCs uniquely display CD141 (thrombomodulin). CD141+VPCs are present in BM aspirates as a rare population and can be expanded ex vivo with a population doubling time of approximately 20 h, generating an elaborate vascular network even under angiogenic factor-deficient conditions and recruiting BM-MSCs to the network as pericyte-like cells. Intramuscular transplantation of a combination of human CD141+VPCs and BM-MSCs at a ratio of 2:1 resulted in limb salvage, blood flow recovery, and regeneration of large vessels in the femoral artery-removed CLI model, with an efficacy superior to that of singular transplantation. Importantly, large arteries and arterioles in dual cell transplantation expressed human CD31 in the intima and human α-smooth muscle actin in media layer at 4 and 12 weeks, likely indicating their lineage commitment to endothelial cells and vascular smooth muscle, respectively, in vivo. Conclusion Dual-cell therapy using BM-derived CD141+ VPCs and BM-MSCs holds potential for further development in clinical trials to treat peripheral artery disease and diabetic ulcers.

Recently, the stem cell-derived secretome, which is the set of proteins expressed by stem cells and secreted into the extracellular space, has been demonstrated as a critical contributor for tissue repair. In this study, we have produced two sets of high concentration secretomes from adipose-derived mesenchymal stem cells (ADSCs) that contain bovine serum or free of exogenous molecules. Through proteomic analysis, we elucidated that proteins related to extracellular matrix organization and growth factor-related proteins are highly secreted by ADSCs. Additionally, the application of ADSC secretome to full skin defect showed accelerated wound closure, enhanced angiogenic response, and complete regeneration of epithelial gaps. Furthermore, the ADSC secretome was capable of reducing scar formation. Finally, we show high-dose injection of ADSC secretome via intraperitoneal or transdermal delivery demonstrated no detectable pathological conditions in various tissues/organs, which supports the notion that ADSC secretome can be safely utilized for tissue repair and regeneration.

Substance P (SP), an injury-inducible messenger that mobilizes bone marrow stem cells and modulates the immune response, has been suggested as a novel target for therapeutic agents. We evaluated the role of SP as an immune cell modulator during the progression of renal ischemic/reperfusion injury (IRI). Unilateral IRI induced the transient expression of endogenous SP and the infiltration of CCR7+ M1 macrophages in injured kidneys. However, SP altered the intrarenal macrophage polarization from CCR7+ M1 macrophages to CD206+ M2 macrophages in injured kidneys. SP also modulated bone marrow-derived neutrophils and mesenchymal stromal cells after IRI. SP treatment for 4 weeks starting one week after unilateral IRI significantly preserved kidney size and length and normal tubular structures and alleviated necrotic tubules, inflammation, apoptosis, and tubulointerstitial fibrosis. The beneficial effects of SP were accompanied by attenuation of intrarenal recruitment of CD4, CD8, and CD20 cells and abnormal angiogenesis. The immunomodulatory effect of SP suggested that SP could be a promising therapeutic target for preventing the progression of acute kidney injury to chronic kidney disease.

Given recent progress in regenerative medicine, we need a means to expand chondrocytes in quantity without losing their regenerative capability. Although many reports have shown that growth factor supplementation can have beneficial effects, the use of growth factor–supplemented basal media has widespread effect on the characteristics of chondrocytes. Chondrocytes were in vitro cultured in the 2 most widely used chondrocyte growth media, conventional chondrocyte culture medium and mesenchymal stem cell (MSC) culture medium, both with and without fibroblast growth factor-2 (FGF2) supplementation. Their expansion rates, expressions of extracellular matrix–related factors, senescence, and differentiation potentials were examined in vitro and in vivo. Our results revealed that chondrocytes quickly dedifferentiated during expansion in all tested media, as assessed by the loss of type II collagen expression. The 2 basal media (chondrocyte culture medium vs. MSC culture medium) were associated with distinct differences in cell senescence. Consistent with the literature, FGF2 was associated with accelerated dedifferentiation during expansion culture and superior redifferentiation upon induction. However, chondrocytes expanded in FGF2-containing conventional chondrocyte culture medium showed MSC-like features, as indicated by their ability to direct ectopic bone formation and cartilage formation. In contrast, chondrocytes cultured in FGF2-supplemented MSC culture medium showed potent chondrogenesis and almost no bone formation. The present findings show that the chosen basal medium can exert profound effects on the characteristics and activity of in vitro–expanded chondrocytes and indicate that right growth factor/medium combination can help chondrocytes retain a high-level chondrogenic potential without undergoing hypertrophic transition.

Mechanical stimulation is a known modulator of survival and proliferation for many cells, including endothelial cells, smooth muscle cells, and bone marrow-derived mesenchymal stem cells. In this study, we found that mechanical strain prevents apoptosis and increases the adhesive ability of dermal fibroblasts in vitro and thus confers the survival advantage in vivo after transplantation of fibroblasts into the full-thickness wound of diabetic mice. Cyclic stretch at a frequency of 0.5 Hz and maximum elongation of 20% stimulates cellular survival mediated by the activation of extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinases (JNKs), and the serine/threonine kinase Akt (AKT). Stretching of the fibroblasts increases the synthesis of extracellular matrix proteins and the formation of denser focal adhesion structures, both of which are required for fibroblast adhesion. The stretched fibroblasts also upregulate the expression of vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α), which enhanced wound healing in vivo. Indeed, preconditioning with mechanical stretch allows better survival of the transplanted fibroblasts, when compared to unstretched control cells, in the wound environment of mice with streptozotocin-induced diabetes and thus accelerates the wound-healing process in these mice.

In Korean, quantitative speech act studies have usually been conducted on single utterances with unspecified sources. In this study, we annotate sentences from the National Institute of Korean Language's Messenger Corpus and the National Petition Corpus, as well as example sentences from an academic paper on contemporary Korean vlogging, and check the discrepancy between human annotation and model prediction. In particular, for sentences with differences in locutionary and illocutionary forces, we analyze the causes of errors to see if stylistic features used in a particular domain affect the correct inference of speech act. Through this, we see the necessity to build and analyze a balanced corpus in various text domains, taking into account cases with different usage roles, e.g., messenger conversations belonging to private conversations and petition corpus/vlogging script that have an unspecified audience.

Tissue injury may create a specific microenvironment for inducing the systemic participation of stromal-like cells in the repair process. Here we show that substance P is an injury-inducible factor that acts early in the wound healing process to induce CD29+ stromal-like cell mobilization. Likewise, mobilization of such cells also occurs in uninjured mice, rats and rabbits if substance P is intravenously injected. Upon further characterization these substance P–mobilized CD29+ cells were found to be similar to stromal cells from a number of connective tissues, including bone marrow (that is, bone marrow stromal cells, or BMSCs). Both substance P injection and transfusion of autologously derived substance P–mobilized CD29+ cells from uninjured rabbits accelerated wound healing in an alkali burn model. Also, epithelial engraftment of the transfused cells into the injured tissue occurred during the wound healing. Finally, using human BMSCs as a test population, we show that substance P stimulates transmigration, cell proliferation, activation of the extracellular signal–related kinases (Erk) 1 and 2 and nuclear translocation of β-catenin in vitro. This finding highlights a previously undescribed function of substance P as a systemically acting messenger of injury and a mobilizer of CD29+ stromal-like cells to participate in wound healing. [ABSTRACT FROM AUTHOR]

Costal cartilage has been proposed as an alternative donor of chondrocytes for articular-cartilage repair. In the present study we compared the initial cell yield of chondrocytes from rabbit costal cartilage and their cell expansion rates in monolayer culture with those of articular cartilage. Costal cartilage gave an approx. 2.6-fold higher cell yield than did articular cartilage. During in vitro culture, CCs (costal chondrocytes) grew faster and displayed approx. 3-fold more cell expansion up to P4 (passage 4) than did ACs (articular chondrocytes). In order to match the degree of dedifferentiation during serial cultivation with the cells' expansion rate, type II collagen expression and the emergence of fibroblastic morphology were monitored at each cell passage. Both ACs and CCs gradually lost their chondrocytic phenotype, changed to fibroblast-like cells and displayed a reduced expression of type II collagen. We then also evaluated the redifferentiation capacity of the expanded ACs and CCs by culturing them at high density in collagen gel. Almost fully dedifferentiated CCs at P4 were successfully redifferentiated into hyaline cartilage, which showed the expression of glycosaminoglycan and type II collagen as well as the formation of lacunae and a territorial matrix. In conclusion, costal cartilage may have advantages over articular cartilage as an alternative donor tissue for autologous chondrocytes on the basis of its higher cell yield, higher cell expansion and successful reversion into hyaline cartilage without ossification in vitro. However, although this experiment with a rabbit model gave a better insight into the problem than other experiments have done, it does not answer definitively the question as to which cells are most appropriate for articular cartilage repair in humans. [ABSTRACT FROM AUTHOR]

Steroids are treated for most inflammatory diseases but cause serious side effects such as diabetes and osteoporosis after their long-term usage. Recently, we identified novel roles of Substance-P (SP) in the suppression of the injury-mediated inflammation and also in stem cell mobilization. In this study, for clinical application of SP as an anti-inflammatory agent, its safety in long-term usage was evaluated with regard to diabetes and osteoporosis. Dexamethasone (DEX) and methylprednisolone (MP) were used as comparative drugs. While DEX-injection for 24 weeks developed severe weight loss, unstable blood glucose, and bone loss, SP-injection did not affect blood glucose and bone mass. MP-injection for 24 weeks also influenced blood glucose and body weight much milder than DEX-injection. After 66 weeks, MP-injection caused unstable blood glucose, alleviation in the age-related increase of body weight, and bone weakness, which was featured by reduction in collagen deposition and trabecular bone volume based on histological and micro CT analysis. However, SP-injection for 66 weeks rather increased collagen deposition, bone volume, and bone density. Therefore, this comparative study suggests that SP, even after long-term usage of effective dose, may not cause side effects such as osteoporosis in comparison to that of DEX and MP and can be developed as an anti-inflammatory agent and/or stem cell mobiliz-er for long-term treatment. [ABSTRACT FROM AUTHOR]