SummaryCutaneous wounds are among the most common soft tissue injuries and are particularly hard to heal in aging. Caloric restriction (CR) is well documented to extend longevity; pharmacologically, profound rejuvenative effects of CR mimetics have been uncovered, especially metformin (MET), resveratrol (RSV), and rapamycin (RAPA). However, locally applied impacts and functional differences of these agents on wound healing remain to be established. Here, we discovered that chronic topical administration of MET and RSV, but not RAPA, accelerated wound healing with improved epidermis, hair follicles, and collagen deposition in young rodents, and MET exerted more profound effects. Furthermore, locally applied MET and RSV improved vascularization of the wound beds, which were attributed to stimulation of adenosine monophosphate‐activated protein kinase (AMPK) pathway, the key mediator of wound healing. Notably, in aged skin, AMPK pathway was inhibited, correlated with impaired vasculature and reduced healing ability. As therapeutic approaches, local treatments of MET and RSV prevented age‐related AMPK suppression and angiogenic inhibition in wound beds. Moreover, in aged rats, rejuvenative effects of topically applied MET and RSV on cell viability of wound beds were confirmed, of which MET showed more prominent anti‐aging effects. We further verified that only MET promoted wound healing and cutaneous integrity in aged skin. These findings clarified differential effects of CR‐based anti‐aging pharmacology in wound healing, identified critical angiogenic and rejuvenative mechanisms through AMPK pathway in both young and aged skin, and unraveled chronic local application of MET as the optimal and promising regenerative agent in treating cutaneous wound defects.

Decline of antioxidant defense after estrogen deficiency leads to oxidative damage in bone marrow-derived mesenchymal stem cells (BMMSCs), resulting a defect of bone formation in osteoporosis. Forkhead box O1 (FoxO1) protein is crucial for defending physiological oxidative damage in bone. But whether FoxO1 is involved in the oxidative damage during osteoporosis is largely unknown. In this study, we found that FoxO1 protein accumulation was decreased in BMMSCs of ovariectomized mice. The decrease of FoxO1 resulted in the suppression of manganese superoxide dismutase (Sod2) and catalase (Cat) expression and accumulation of reactive oxygen species (ROS), inhibiting the osteogenic differentiation of BMMSCs. The decline of FoxO1 protein was caused by tumor necrosis factor-alpha (TNF-a) accumulated after estrogen deficiency. Mechanistically, TNF-a activated NF-jB pathway to promote microRNA-705 expression, which function as a repressor of FoxO1 through post-transcriptional regulation. Inhibition of NFjB pathway or knockdown of miR-705 largely prevented the decline of FoxO1-mediated antioxidant defense caused by TNF-a and ameliorated the oxidative damage in osteoporotic BMMSCs. Moreover, the accumulated ROS further activated NF-jB pathway with TNF-a, which formed a feed-forward loop to persistently inhibiting FoxO1 protein accumulation in BMMSCs. In conclusion, our study revealed that the decline of FoxO1 is an important etiology factor of osteoporosis and unclosed a novel mechanism of FoxO1 regulation by TNF-a. These findings suggested a close correlation between inflammation and oxidative stress in stem cell dysfunction during degenerative bone diseases. STEM CELLS 2016;34:1054-1067 SIGNIFICANCE STATEMENTThis study revealed two novel findings. (a) The decline of FOXO1 protein after estrogen deficiency is a crucial etiological factor of osteoporosis. Previous study confirmed that FOXO1 is an important mediator of skeleton resistance to physiologic oxidative stress. Our study further showed that oxidative damage in osteoporosis is, at least partly, caused by FOXO1 dysfunction, suggesting FOXO1 is a potential target for osteoporosis prevention and treatment. (b) TNF-a decreased FOXO1-mediated antioxidant defense through post-transcriptional regulation by miR-705. This study uncovered that TNF-a directly inhibits antioxidant defense to aggravate oxidative stress damage, suggesting a central role of TNF-a in oxidative damage regulation. Since oxidative stress could induce inflammatory events, these results unclosed a novel network between inflammation and oxidative stress, suggesting intervention of inflammation signaling is a potential strategy for recovery of mesenchymal stem cell dysfunction and treatment of degenerative bone diseases.

Background As the major interface between the body and the external environment, the skin is liable to various injuries. Skin injuries often lead to severe disability, and the exploration of promising therapeutic strategies is of great importance. Exogenous mesenchymal stem cell (MSC)-based therapy is a potential strategy due to the apparent therapeutic effects, while the underlying mechanism is still elusive. Interestingly, we observed the extensive apoptosis of exogenous bone marrow mesenchymal stem cells (BMMSCs) in a short time after transplantation in mouse skin wound healing models. Considering the roles of extracellular vesicles (EVs) in intercellular communication, we hypothesized that the numerous apoptotic bodies (ABs) released during apoptosis may partially contribute to the therapeutic effects. Methods ABs derived from MSCs were extracted, characterized, and applied in mouse skin wound healing models, and the therapeutic effects were evaluated. Then, the target cells of ABs were explored, and the effects of ABs on macrophages were investigated in vitro. Results We found ABs derived from MSCs promoted cutaneous wound healing via triggering the polarization of macrophages towards M2 phenotype. In addition, the functional converted macrophages further enhanced the migration and proliferation abilities of fibroblasts, which together facilitated the wound healing process. Conclusions Collectively, our study demonstrated that transplanted MSCs promoted cutaneous wound healing partially through releasing apoptotic bodies which could convert the macrophages towards an anti-inflammatory phenotype that plays a crucial role in the tissue repair process.

Rational: Senescence of mesenchymal stem cells (MSCs) and the related functional decline of osteogenesis have emerged as the critical pathogenesis of osteoporosis in aging. Resveratrol (RESV), a small molecular compound that safely mimics the effects of dietary restriction, has been well documented to extend lifespan in lower organisms and improve health in aging rodents. However, whether RESV promotes function of senescent stem cells in alleviating age-related phenotypes remains largely unknown. Here, we intend to investigate whether RESV counteracts senescence-associated bone loss via osteogenic improvement of MSCs and the underlying mechanism.Methods: MSCs derived from bone marrow (BMMSCs) and the bone-specific, senescence-accelerated, osteoblastogenesis/osteogenesis-defective mice (the SAMP6 strain) were used as experimental models. In vivo application of RESV was performed at 100 mg/kg intraperitoneally once every other day for 2 months, and in vitro application of RESV was performed at 10 μM. Bone mass, bone formation rates and osteogenic differentiation of BMMSCs were primarily evaluated. Metabolic statuses of BMMSCs and the mitochondrial activity, transcription and morphology were also examined. Mitofilin expression was assessed at both mRNA and protein levels, and short hairpin RNA (shRNA)-based gene knockdown was applied for mechanistic experiments.Results: Chronic intermittent application of RESV enhances bone formation and counteracts accelerated bone loss, with RESV improving osteogenic differentiation of senescent BMMSCs. Furthermore, in rescuing osteogenic decline under BMMSC senescence, RESV restores cellular metabolism through mitochondrial functional recovery via facilitating mitochondrial autonomous gene transcription. Molecularly, in alleviating senescence-associated mitochondrial disorders of BMMSCs, particularly the mitochondrial morphological alterations, RESV upregulates Mitofilin, also known as inner membrane protein of mitochondria (Immt) or Mic60, which is the core component of the mitochondrial contact site and cristae organizing system (MICOS). Moreover, Mitofilin is revealed to be indispensable for mitochondrial homeostasis and osteogenesis of BMMSCs, and that insufficiency of Mitofilin leads to BMMSC senescence and bone loss. More importantly, Mitofilin mediates resveratrol-induced mitochondrial and osteogenic improvements of BMMSCs in senescence.Conclusion: Our findings uncover osteogenic functional improvements of senescent MSCs as critical impacts in anti-osteoporotic practice of RESV, and unravel Mitofilin as a novel mechanism mediating RESV promotion on mitochondrial function in stem cell senescence.

Inflammatory response plays a critical role in myocardial infarction (MI) repair. The neutrophil apoptosis and subsequent macrophage ingestion can result in inflammation resolution and initiate regeneration, while the therapeutic strategy that simulates and enhances this natural process has not been established. Here, we constructed engineered neutrophil apoptotic bodies (eNABs) to simulate natural neutrophil apoptosis, which regulated inflammation response and enhanced MI repair. The eNABs were fabricated by combining natural neutrophil apoptotic body membrane which has excellent inflammation-tropism and immunoregulatory properties, and mesoporous silica nanoparticles loaded with hexyl 5-aminolevulinate hydrochloride (HAL). The eNABs actively targeted to macrophages and the encapsulated HAL simultaneously initiated the biosynthesis pathway of heme to produce anti-inflammatory bilirubin after intracellular release, thereby further enhancing the anti-inflammation effects. In in vivo studies, the eNABs efficiently modulated inflammation responses in the infarcted region to ameliorate cardiac function. This study demonstrates an effective biomimetic construction strategy to regulate macrophage functions for MI repair.

Estrogen deficiency is one of the most frequent causes of osteoporosis in postmenopausal women. Under chronic inflammatory conditions caused by estrogen deficiency, activated T cells contribute to elevated levels of proinflammatory cytokines, impaired osteogenic differentiation capabilities of bone marrow mesenchymal stem cells (BMMSCs), and disturbed regulatory T cell (Treg)/Th17 cell balance. However, therapeutic strategies that re-establish immune homeostasis in this disorder have not been well developed. Here, we produced T cell-depleting nanoparticles (TDNs) that ameliorated the osteopenia phenotype and rescued the osteogenic deficiency of BMMSCs in ovariectomized (OVX) mice. TDNs consist of monocyte chemotactic protein-1 (MCP-1)-encapsulated mesoporous silica nanoparticles as the core and Fas-ligand (FasL) as the corona. We showed that the delicate design of the TDNs enables rapid release of MCP-1 to recruit activated T cells and then induces their apoptosis through the conjugated FasL both in vitro and in vivo . Apoptotic signals recognized by macrophages help skew the Treg/Th17 cell balance and create an immune tolerant state, further attenuating the osteogenic deficiency of BMMSCs and the osteopenia phenotype. Mechanistically, we found that the therapeutic effects of TDNs were partially mediated by apoptotic T cell-derived extracellular vesicles (ApoEVs), which promoted macrophage transformation towards the M2 phenotype. These findings demonstrate that TDNs may represent a promising strategy for treating osteoporosis and other immune disorders.

Spindle cell B-cell lymphoma is a rare morphologic variant of B-cell lymphoma that is generally associated with follicle center cell origin. It is typically found on the skin and presents as single nodule or plaque with a diameter of several centimeters. It is also characterized by abnormal spindle cells with elongated or spindle-shaped nuclei, and usually stained positive for Bcl-6 and negative for multiple myeloma oncogene 1 (MUM-1). In this report, we describe a giant primary cutaneous spindle cell B-cell lymphoma measured 20 cm × 25 cm, substantially larger than all the previously reported cases. Histologic examination revealed that the neoplasm was mainly located in the dermis and subcutaneous fat, and had infiltrated into striated muscles of the patient's back. The neoplasm cells contained elongated or spindle-shaped nuclei. Immunohistochemistry results demonstrated that the neoplasm cells were stained positive for CD20, CD79, and Bcl-6, negative for Bcl-2 and MUM-1, and focally positive for CD5, CD10, CD31, and CD43. These results collectively indicated that the neoplasm was of follicle center cell origin. The neoplasm was excised and the patient was still alive without systemic involvement after 4 years of follow-up.

Osteonecrosis of the femoral head (ONFH) is a common refractory orthopedic disease with multiple etiologies that more frequently occurs in middle-aged and young people. ONFH is the main cause of hip replacement in young patients. Since Professor Hernigou first reported the use of stem cells in the treatment of early stage ONFH, a large number of studies have demonstrated the potential of stem cells in the treatment of adult patients with ONFH. With the rise of interdisciplinary stem cell therapy combined with platelet-rich plasma therapy, gene therapy or other methods have gradually attracted the attention of researchers. This article summarizes the current advances in stem cell therapy for ONFH, as well as the problems and challenges, which may provide reference for further research.