The stem cell movement

Understanding the molecular mechanism of regeneration through apoptosis-induced compensatory proliferation studies - updates and future aspects

AICP is a crucial process that maintaining tissue homeostasis and regeneration. In the past, cell death was perceived merely as a means to discard cells without functional consequences. However, during regeneration, effector caspases orchestrate apoptosis, releasing signals that activate stem cells, thereby compensating for tissue loss across various animal models. Despite significant progress, the activation of Wnt3a by caspase-3 remains a focal point of research gaps in AICP mechanisms, spanning from lower to higher regenerative animals. This inquiry into the molecular intricacies of caspase-3-induced Wnt3a activation contributes to a deeper understanding of the links between regeneration and cancer mechanisms. Our report provides current updates on AICP pathways, delineating research gaps and highlighting the potential for future investigations aimed at enhancing our comprehension of this intricate process.

In vitro generation of epidermal keratinocytes from human CD34-positive hematopoietic stem cells

The epidermis is largely composed of keratinocytes (KCs), and the proliferation and differentiation of KCs from the stratum basale to the stratum corneum is the cellular hierarchy present in the epidermis. In this study, we explore the differentiation abilities of human hematopoietic stem cells (HSCs) into KCs. Cultured HSCs positive for CD34, CD45, and CD133 with prominent telomerase activity were induced with keratinocyte differentiation medium (KDM), which is composed of bovine pituitary extract (BPE), epidermal growth factor (EGF), insulin, hydrocortisone, epinephrine, transferrin, calcium chloride (CaCl2), bone morphogenetic protein 4 (BMP4), and retinoic acid (RA). Differentiation was monitored through the expression of cytokeratin markers K5 (keratin 5), K14 (keratin 14), K10 (keratin 10), K1 (keratin 1), transglutaminase 1 (TGM1), involucrin (IVL), and filaggrin (FLG) on day 0 (D0), day 6 (D6), day 11 (D11), day 18 (D18), day 24 (D24), and day 30 (D30) using immunocytochemistry, fluorescence microscopy, flow cytometry, qPCR, and Western blotting. The results revealed the expression of K5 and K14 genes in D6 cells (early keratinocytes), K10 and K1 genes in D11-D18 cells (mature keratinocytes) with active telomerase enzyme, and FLG, IVL, and TGM1 in D18-D24 cells (terminal keratinocytes), and by D30, the KCs were completely enucleated similar to cornified matrix. This method of differentiation of HSCs to KCs explains the cellular order exists in the normal epidermis and opens the possibility of exploring the use of human HSCs in the epidermal differentiation.

Sonomechanobiology: Vibrational stimulation of cells and its therapeutic implications

All cells possess an innate ability to respond to a range of mechanical stimuli through their complex internal machinery. This comprises various mechanosensory elements that detect these mechanical cues and diverse cytoskeletal structures that transmit the force to different parts of the cell, where they are transcribed into complex transcriptomic and signaling events that determine their response and fate. In contrast to static (or steady) mechanostimuli primarily involving constant-force loading such as compression, tension, and shear (or forces applied at very low oscillatory frequencies (≤ 1 Hz) that essentially render their effects quasi-static), dynamic mechanostimuli comprising more complex vibrational forms (e.g., time-dependent, i.e., periodic, forcing) at higher frequencies are less well understood in comparison. We review the mechanotransductive processes associated with such acoustic forcing, typically at ultrasonic frequencies (> 20 kHz), and discuss the various applications that arise from the cellular responses that are generated, particularly for regenerative therapeutics, such as exosome biogenesis, stem cell differentiation, and endothelial barrier modulation. Finally, we offer perspectives on the possible existence of a universal mechanism that is common across all forms of acoustically driven mechanostimuli that underscores the central role of the cell membrane as the key effector, and calcium as the dominant second messenger, in the mechanotransduction process.

Regulation of Transplanted Cell Homing by FGF1 and PDGFB after Doxorubicin Myocardial Injury

There is no effective treatment for the total recovery of myocardial injury caused by an anticancer drug, doxorubicin (Dox). In this study, using a Dox-induced cardiac injury model, we compared the cardioprotective effects of ventricular cells harvested from 11.5-day old embryonic mice (E11.5) with those from E14.5 embryos. Our results indicate that tail-vein-infused E11.5 ventricular cells are more efficient at homing into the injured adult myocardium, and are more angiogenic, than E14.5 ventricular cells. In addition, E11.5 cells were shown to mitigate the cardiomyopathic effects of Dox. In vitro, E11.5 ventricular cells were more migratory than E14.5 cells, and RT-qPCR analysis revealed that they express significantly higher levels of cytokine receptors Fgfr1, Fgfr2, Pdgfra, Pdgfrb and Kit. Remarkably, mRNA levels for Fgf1, Fgf2, Pdgfa and Pdgfb were also found to be elevated in the Dox-injured adult heart, as were the FGF1 and PDGFB protein levels. Addition of exogenous FGF1 or PDGFB was able to enhance E11.5 ventricular cell migration in vitro, and, whereas their neutralizing antibodies decreased cell migration. These results indicate that therapies raising the levels of FGF1 and PDGFB receptors in donor cells and or corresponding ligands in an injured heart could improve the efficacy of cell-based interventions for myocardial repair.

Extracellular vesicles for tissue repair and regeneration: Evidence, challenges and opportunities

Extracellular vesicles (EVs) are biological nanoparticles naturally secreted by cells, acting as delivery vehicles for molecular messages. During the last decade, EVs have been assigned multiple functions that have established their potential as therapeutic mediators for a variety of diseases and conditions. In this review paper, we report on the potential of EVs in tissue repair and regeneration. The regenerative properties that have been associated with EVs are explored, detailing the molecular cargo they carry that is capable of mediating such effects, the signaling cascades triggered in target cells and the functional outcome achieved. EV interactions and biodistribution in vivo that influence their regenerative effects are also described, particularly upon administration in combination with biomaterials. Finally, we review the progress that has been made for the successful implementation of EV regenerative therapies in a clinical setting.

Understanding stem cells and its pivotal role in regenerative medicine

Stem cells (SCs) are clonogenic cells that develop into the specialized cells which later responsible for making up various types of tissue in the human body. SCs are not only the appropriate source of information for cell division, molecular and cellular processes, and tissue homeostasis but also one of the major putative biological aids to diagnose and cure various degenerative diseases. This study emphasises on various research outputs that occurred in the past two decades. This will give brief information on classification, differentiation, detection, and various isolation techniques of SCs. Here, the various signalling pathways which includes WNT, Sonic hedgehog, Notch, BMI1 and C-met pathways and how does it effect on the regeneration of various classes of SCs and factors that regulates the potency of the SCs are also been discussed. We also focused on the application of SCs in the area of regenerative medicine along with the cellular markers that are useful as salient diagnostic or curative tools or in both, by the process of reprogramming, which includes diabetes, cancer, cardiovascular disorders and neurological disorders. The biomarkers that are mentioned in various literatures and experiments include PDX1, FOXA2, HNF6, and NKX6-1 (for diabetes); CD33, CD24, CD133 (for cancer); c-Kit, SCA-1, Wilm's tumor 1 (for cardiovascular disorders); and OCT4, SOX2, c-MYC, EN1, DAT and VMAT2 (for neurological disorders). In this review, we come to know the advancements and scopes of potential SC-based therapies, its diverse applications in clinical fields that can be helpful in the near future.

Bimodal Imaging-Visible Nanomedicine Integrating CXCR4 and VEGFa Genes Directs Synergistic Reendothelialization of Endothelial Progenitor Cells

A major challenge to treat vascular endothelial injury is the restoration of endothelium integrity in which endothelial progenitor cells (EPCs) plays a central role. Transplantation of EPCs as a promising therapeutic means is subject to two interrelated processes, homing and differentiation of EPCs in vivo, and thus a lack of either one may greatly affect the outcome of EPC-based therapy. Herein, a polymeric nanocarrier is applied for the codelivery of CXCR4 and VEGFa genes to simultaneously promote the migration and differentiation of EPCs. Moreover, MRI T2 contrast agent SPION and NIR dye Cy7.5 are also loaded into the nanocarrier in order to track EPCs in vivo. Based on the synergistic effect of the two codelivered genes, an improved reendothelialization of EPCs is achieved in a rat carotid denuded model. The results show the potential of this bimodal imaging-visible nanomedicine to improve the performance of EPCs in repairing arterial injury, which may push forward the stem cell-based therapy of cardiovascular disease.

Coronary vessel formation in development and disease: mechanisms and insights for therapy

The formation of new blood vessels after myocardial infarction (MI) is essential for the survival of existing and regenerated cardiac tissue. However, the extent of endogenous revascularization after MI is insufficient, and MI can often result in ventricular remodelling, progression to heart failure and premature death. The neutral results of numerous clinical trials that have evaluated the efficacy of angiogenic therapy to revascularize the infarcted heart reflect our poor understanding of the processes required to form a functional coronary vasculature. In this Review, we describe the latest advances in our understanding of the processes involved in coronary vessel formation, with mechanistic insights taken from developmental studies. Coronary vessels originate from multiple cellular sources during development and form through a number of distinct and carefully orchestrated processes. The ectopic reactivation of developmental programmes has been proposed as a new paradigm for regenerative medicine, therefore, a complete understanding of these processes is crucial. Furthermore, knowledge of how these processes differ between the embryonic and adult heart, and how they might be more closely recapitulated after injury are critical for our understanding of regenerative biology, and might facilitate the identification of tractable molecular targets to therapeutically promote neovascularization and regeneration of the infarcted heart.

Assessment of proliferation, migration and differentiation potentials of bone marrow mesenchymal stem cells labeling with silica-coated and amine-modified superparamagnetic iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles have been widely used for cell labeling in preclinical and clinical studies, to improve labeling efficiency, particle conjugation and surface modifications are developed, but some modified SPIONs exert side-effect on physiological activity of cells, which cannot be served as ideal cell tracker. In this study, amine-modified silica-coated SPIO (SPIO@SiO₂-NH₂, SPIO@S-N) nanoparticles were used to label bone marrow derived mesenchymal stem cells (BM-MSCs), then the stem cell potentials were evaluated. It was found BM-MSCs could be efficiently labeled by SPIO@S-N nanoparticles. After labeling, the BM-MSCs viability kept well and the migration ability increased, but the osteogenesis and adipogenesis potentials were not impaired. In steroid associated osteonecrosis (SAON) bone defect model, stem cell implantation was performed by injection of SPIO@S-N labeled BM-MSCs into marrow cavity locally, it was found the SPIO positive cells homed to the periphery of defect region in control group, but were recruited to the defect region in poly lactic-coglycolic acid/tricalcium phosphate (PLGA/TCP) scaffold implantation group. In conclusion, SPIO@S-N nanoparticles promoted migration while retained proliferation and differentiation ability of BM-MSCs, implying this kind of nanoparticles could be served not only an ideal tracking marker but also an accelerator for stem cell homing during tissue repair.

Tonsil-derived stem cells as a new source of adult stem cells

Located near the oropharynx, the tonsils are the primary mucosal immune organ. Tonsil tissue is a promising alternative source for the high-yield isolation of adult stem cells, and recent studies have reported the identification and isolation of tonsil-derived stem cells (T-SCs) from waste surgical tissue following tonsillectomies in relatively young donors (i.e., under 10 years old). As such, T-SCs offer several advantages, including superior proliferation and a shorter doubling time compared to bone marrow-derived mesenchymal stem cells (MSCs). T-SCs also exhibit multi-lineage differentiation, including mesodermal, endodermal (e.g., hepatocytes and parathyroid-like cells), and even ectodermal cells (e.g., Schwann cells). To this end, numbers of researchers have evaluated the practical use of T-SCs as an alternative source of autologous or allogenic MSCs. In this review, we summarize the details of T-SC isolation and identification and provide an overview of their application in cell therapy and regenerative medicine.

Allogeneic Adipose-Derived Mesenchymal Stem Cell Transplantation Enhances the Expression of Angiogenic Factors in a Mouse Acute Hindlimb Ischemic Model

Cell migration and molecular mechanisms during healing of damaged vascular or muscle tissues are emerging fields of interest worldwide. The study herein focuses on evaluating the role of allogenic adipose-derived mesenchymal stem cells (ADMSCs) in restoring damaged tissues. Using a hindlimb ischemic mouse model, ADMSC-mediated induction of cell migration and gene expression related to myocyte regeneration and angiogenesis were evaluated. ADMSCs were labeled with GFP (ADMSC-GFP). The proximal end of the femoral blood vessel of mice (over 6 months of age) are ligated at two positions then cut between the two ties. Hindlimb ischemic mice were randomly divided into two groups: Group I (n = 30) which was injected with PBS (100 μL) and Group II (n = 30) which was transplanted with ADMSC-GFP (10⁶ cells/100 μL PBS) at the rectus femoris muscle. The migration of ADMSC-GFP in hindlimb was analyzed by UV-Vis system. The expression of genes related to angiogenesis and muscle tissue repair was quantified by real-time RT-PCR. The results showed that ADMSCs existed in the grafted hindlimb for 7 days. Grafted cells migrated to other damaged areas such as thigh and heel. In both groups the ischemic hindlimb showed an increased expression of several angiogenic genes, including Flt-1, Flk-1, and Ang-2. In particular, the expression of Ang-2 and myogenic-related gene MyoD was significantly increased in the ADMSC-treated group compared to the PBS-treated (control) group; the expression increased at day 28 compared to day 3. The other factors, such as VE-Cadherin, HGF, CD31, Myf5, and TGF-β, were also more highly expressed in the ADMSC-treated group than in the control group. Thus, grafted ADMSCs were able to migrate to other areas in the injured hindlimb, persist for approximately 7 days, and have a significantly positive impact on stimulating expression of myogenic- and angiogenesis-related genes.

Cytoskeletal control of nuclear morphology and stiffness are required for OPN-induced bone-marrow-derived mesenchymal stem cell migration

During cell migration, the movement of the nucleus must be coordinated with the cytoskeletal dynamics that influence the efficiency of cell migration. Our previous study demonstrated that osteopontin (OPN) significantly promotes the migration of bone-marrow-derived mesenchymal stem cells (BMSCs). However, the mechanism that regulates nuclear mechanics of the cytoskeleton during OPN-promoted BMSC migration remains unclear. In this study, we investigated how the actin cytoskeleton influences nuclear mechanics in BMSCs. We assessed the morphology and mechanics of the nuclei in the OPN-treated BMSCs subjected to disruption or polymerization of the actin cytoskeleton. We found that disruption of actin organization by cytochalasin D (Cyto D) resulted in a decrease in the nuclear projected area and nuclear stiffness. Stabilizing the actin assembly with jasplakinolide (JASP) resulted in an increase in the nuclear projected area and nuclear stiffness. SUN1 (Sad-1/UNC-84 1) is a component of the LINC (linker of nucleoskeleton and cytoskeleton) complex involved in the connections between the nucleus and the cytoskeleton. We found that SUN1 depletion by RNAi decreased the nuclear stiffness and OPN-promoted BMSC migration. Thus, the F-actin cytoskeleton plays an important role in determining the morphology and mechanical properties of the nucleus. We suggest that the cytoskeletal-nuclear interconnectivity through SUN1 proteins plays an important role in OPN-promoted BMSC migration.

Thermogels for Stem Cell Culture

The ultimate goal of stem cell therapy is to replace surgery with injection of stem cells into a trauma site with localized cell proliferation and differentiation to heal a particular tissue or organ. Thermogelling composite systems have been investigated as biodegradable, injectable 3D scaffolds for stem cell proliferation and differentiation. These thermogels have been successfully used as cultivating media; however, certain additives have proved necessary for the stem cells to be able to differentiate in vitro (e.g. graphene oxide for adipogenesis and calcium phosphate crystals for osteogenesis). This chapter summarizes the great strides that have been made and what remains to be done in this exciting field.

Bradykinin-mediated Ca2+ signalling regulates cell growth and mobility in human cardiac c-Kit+ progenitor cells

Our recent study showed that bradykinin increases cell cycling progression and migration of human cardiac c‐Kit⁺ progenitor cells by activating pAkt and pERK1/2 signals. This study investigated whether bradykinin‐mediated Ca²⁺ signalling participates in regulating cellular functions in cultured human cardiac c‐Kit⁺ progenitor cells using laser scanning confocal microscopy and biochemical approaches. It was found that bradykinin increased cytosolic free Ca²⁺ (Cai2+) by triggering a transient Ca²⁺ release from ER IP3Rs followed by sustained Ca²⁺ influx through store‐operated Ca²⁺ entry (SOCE) channel. Blockade of B2 receptor with HOE140 or IP3Rs with araguspongin B or silencing IP3R3 with siRNA abolished both Ca²⁺ release and Ca²⁺ influx. It is interesting to note that the bradykinin‐induced cell cycle progression and migration were not observed in cells with siRNA‐silenced IP3R3 or the SOCE component TRPC1, Orai1 or STIM1. Also the bradykinin‐induced increase in pAkt and pERK1/2 as well as cyclin D1 was reduced in these cells. These results demonstrate for the first time that bradykinin‐mediated increase in free Cai2+ via ER‐IP3R3 Ca²⁺ release followed by Ca²⁺ influx through SOCE channel plays a crucial role in regulating cell growth and migration via activating pAkt, pERK1/2 and cyclin D1 in human cardiac c‐Kit⁺ progenitor cells.

An open-label proof-of-concept study of intrathecal autologous bone marrow mononuclear cell transplantation in intellectual disability

Background

The underlying pathophysiology in intellectual disability (ID) involves abnormalities in dendritic branching and connectivity of the neuronal network. This limits the ability of the brain to process information. Conceptually, cellular therapy through its neurorestorative and neuroregenerative properties can counteract these pathogenetic mechanisms and improve neuronal connectivity. This improved networking should exhibit as clinical efficacy in patients with ID.

Methods

To assess the safety and efficacy of cellular therapy in patients with ID, we conducted an open-label proof-of-concept study from October 2011 to December 2015. Patients were divided into two groups: intervention group (n = 29) and rehabilitation group (n = 29). The intervention group underwent cellular transplantation consisting of intrathecal administration of autologous bone marrow mononuclear cells and standard neurorehabilitation. The rehabilitation group underwent only standard neurorehabilitation.

The results of the symptomatic outcomes were compared between the two groups. In the intervention group analysis, the outcome measures used were the intelligence quotient (IQ) and the Wee Functional Independence Measure (Wee-FIM). To compare the pre-intervention and post-intervention results, statistical analysis was done using Wilcoxon’s matched-pairs test for Wee-FIM scores and McNemar’s test for symptomatic improvements and IQ. The effect of age and severity of the disorder were assessed for their impact on the outcome of intervention. Positron emission tomography-computed tomography (PET-CT) brain scan was used as a monitoring tool to study effects of the intervention. Adverse events were monitored for the safety of cellular therapy.

Results

On symptomatic analysis, greater improvements were seen in the intervention group as compared to the rehabilitation group. In the intervention group, the symptomatic improvements, IQ and Wee-FIM were statistically significant. A significantly better outcome of the intervention was found in the paediatric age group (<18 years) and patients with milder severity of ID. Repeat PET-CT scan in three patients of the intervention group showed improved metabolism in the frontal, parietal cortex, thalamus, mesial temporal structures and cerebellum. No major adverse events were witnessed.

Conclusions

Cellular transplantation with neurorehabilitation is safe and effective for the treatment of underlying brain deficits in ID.

Trial registration

ClinicalTrials.gov NCT02245724. Registered 12 September 2014.

Chromatin organization regulated by EZH2-mediated H3K27me3 is required for OPN-induced migration of bone marrow-derived mesenchymal stem cells

Osteopontin (OPN) is a chemokine-like extracellular matrix-associated protein involved in the migration of bone marrow-derived mesenchymal stem cells (BMSCs). An increasing number of studies have found that chromatin organization may affect cellular migration. However, whether OPN regulates chromatin organization is not understood, nor are the underlying molecular mechanisms. In this study, we investigated the link between chromatin organization and BMSC migration and demonstrated that OPN-mediated BMSC migration leads to elevated levels of heterochromatin marker histone H3 lysine 27 trimethylation (H3K27me3) through the methyltransferase EZH2. The expression of EZH2 reorganizes the chromatin structure of BMSCs. Pharmacological inhibition or depletion of EZH2 blocks BMSC migration. Moreover, using an atomic force microscope (AFM), we found that chromatin decondensation alters the mechanical properties of the nucleus. In addition, inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) signals represses OPN-promoted chromatin condensation and cell migration. Thus, our results identify a mechanism by which ERK1/2 signalling drives specific chromatin modifications in BMSCs, which alters chromatin organization and thereby enables OPN-mediated BMSC migration.

Short-Term Homing of Hyaluronan-Primed Cells: Therapeutic Implications for Osteoarthritis Treatment

The evaluation of key factors modulating cell homing following injection can provide new insights in the comprehension of unsolved biological questions about the use of cell therapies for osteoarthritis (OA). The main purpose of this in vivo study was to investigate the biodistribution of an intra-articular injection of mesenchymal stromal cells (MSCs) and bone marrow concentrate (BMC) in a rabbit OA model and whether the additional use of sodium hyaluronate (HA) could modulate their migration and delay joint degeneration. OA was surgically induced in adult male New Zealand rabbits. A group of animals was used to test the biodistribution of labeled cells alone or with HA at 7 and 14 days to investigate cell migration. The efficacy of treatments was evaluated in other experimental groups at 2 months. Histology and immunohistochemistry for markers identifying anabolic and catabolic processes in the cartilage and meniscus, or macrophage subset population in the synovial membrane, were performed. Kruskal-Wallis test, followed by post hoc Dunn's test, and Spearman's rank-order correlation method were used. MSCs and BMC preferentially migrate toward tissue areas showing OA features in the meniscus and cartilage and in detail near inflammatory zones in the synovial membrane. The combination with HA contributed to boost cell migration toward articular cartilage. In general, both labeled cells combined with HA were found near cell cluster and fissures in the cartilage and meniscus, respectively, and close to areas of synovial membrane showing mainly anti-inflammatory macrophages. A promotion of joint repair was observed at different levels for all treatments, although BMC-HA treatment resulted as the best strategy to support joint repair. This last, displayed a good protein expression of type II collagen in the cartilage, as well as the presence of anti-inflammatory macrophages in the synovial membrane at 2 months from the treatment. Studies tracking cell biodistribution indicate that priming progenitor cells with HA modulated cell homing favoring not only attachment but also their integration within articular cartilage.

Homing of endogenous bone marrow mesenchymal stem cells to rat infarcted myocardium via ultrasound-mediated recombinant SDF-1α adenovirus in microbubbles

Stem cells can promote myocardial regeneration and accelerate the formation of new blood vessels. As such, transplanted stem cells represent a promising treatment modality for acute myocardial infarction (AMI). Stem cells spontaneously home to the infarcted myocardium using chemotaxis, in which the stromal cell-derived factor (SDF-1α) has been shown to be one of the most important chemokines. However, spontaneously secreted SDF-1α is short-lived, and therefore does not meet the needs of tissue repair. In this study, adenoviruses carrying SDF-1α genes were loaded on microbubble carriers and the adenoviruses were released into AMI rats by ultrasound targeted microbubble destruction. The possibility of in vivo self-transplantation of bone marrow mesenchymal stem cells (BMSCs) induced by overexpression of SDF-1α in the infarcted myocardium was explored by detecting the number of BMSCs homing from the peripheral blood to the myocardial infarcts. The concentration of SDF-1α in peripheral blood was significantly higher after transfection, and the number of BMSCs was significantly higher in the peripheral blood and infarcted area. Further analyses indicated that the number of homing BMSCs increased with increased SDF-1α expression. In conclusion, our results suggest that ultrasound mediated transduction of exogenous SDF-1α genes into myocardial infarcted AMI rats can effectively promote the homing of endogenous BMSCs into the heart. Moreover, the number of homing stem cells was controlled by the level of SDF-1α expression.

Cardiac Progenitor Cells and the Interplay with Their Microenvironment

The microenvironment plays a crucial role in the behavior of stem and progenitor cells. In the heart, cardiac progenitor cells (CPCs) reside in specific niches, characterized by key components that are altered in response to a myocardial infarction. To date, there is a lack of knowledge on these niches and on the CPC interplay with the niche components. Insight into these complex interactions and into the influence of microenvironmental factors on CPCs can be used to promote the regenerative potential of these cells. In this review, we discuss cardiac resident progenitor cells and their regenerative potential and provide an overview of the interactions of CPCs with the key elements of their niche. We focus on the interaction between CPCs and supporting cells, extracellular matrix, mechanical stimuli, and soluble factors. Finally, we describe novel approaches to modulate the CPC niche that can represent the next step in recreating an optimal CPC microenvironment and thereby improve their regeneration capacity.

Concise Review: Challenges in Regenerating the Diabetic Heart: A Comprehensive Review

Stem cell therapy is one of the promising regenerative strategies developed to improve cardiac function in patients with ischemic heart diseases (IHD). However, this approach is limited in IHD patients with diabetes due to a progressive decline in the regenerative capacity of stem cells. This decline is mainly attributed to the metabolic memory incurred by diabetes on stem cell niche and their systemic cues. Understanding the molecular pathways involved in the diabetes-induced deterioration of stem cell function will be critical for developing new cardiac regeneration therapies. In this review, we first discuss the most common molecular alterations occurring in the diabetic stem cells/progenitor cells. Next, we highlight the key signaling pathways that can be dysregulated in a diabetic environment and impair the mobilization of stem/progenitor cells, which is essential for the transplanted/endogenous stem cells to reach the site of injury. We further discuss the possible methods of preconditioning the diabetic cardiac progenitor cell (CPC) with an aim to enrich the availability of efficient stem cells to regenerate the diseased diabetic heart. Finally, we propose new modalities for enriching the diabetic CPC through genetic or tissue engineering that would aid in developing autologous therapeutic strategies, improving the proliferative, angiogenic, and cardiogenic properties of diabetic stem/progenitor cells. Stem Cells 2017;35:2009-2026.

Prediction of early recurrence of hepatocellular carcinoma within the Milan criteria after radical resection

Approximately 50% hepatocellular carcinoma patients meeting the Milan criteria utilized to develop an improved prognostic model for predicting the recurrence in these patients. Using univariate and multivariate analysis, cytokeratin-19 and glypican-3 expression patterns, tumor number and histological grading from eight putative prognostic factors comprised the risk factor scoring model to predict the tumor recurrence. In the training cohort, the area under roc curve (AUC) value of the model was 0.715 [95% confidence interval (CI) = 0.645-0.786, P<0.001], which was the highest among all the parameters. The performance of the model was assessed using an independent validation cohort, wherein the AUC value was 0.760 (95% CI=0.647-0.874, P<0.001), which was higher than the other factors. The results indicated that model had high performance with adequate discrimination ability. Moreover, it significantly improved the predictive capacity for the recurrence in patients with hepatocellular carcinoma within the Milan criteria after radical resection.

Decreased nuclear stiffness via FAK-ERK1/2 signaling is necessary for osteopontin-promoted migration of bone marrow-derived mesenchymal stem cells

Migration of bone marrow-derived mesenchymal stem cells (BMSCs) plays an important role in many physiological and pathological settings, including wound healing. During the migration of BMSCs through interstitial tissues, the movement of the nucleus must be coordinated with the cytoskeletal dynamics, which in turn affects the cell migration efficiency. Our previous study indicated that osteopontin (OPN) significantly promotes the migration of rat BMSCs. However, the nuclear behaviors and involved molecular mechanisms in OPN-mediated BMSC migration are largely unclear. In the present study, using an atomic force microscope (AFM), we found that OPN could decrease the nuclear stiffness of BMSCs and reduce the expression of lamin A/C, which is the main determinant of nuclear stiffness. Increased lamin A/C expression attenuates BMSC migration by increasing nuclear stiffness. Decreased lamin A/C expression promotes BMSC migration by decreasing nuclear stiffness. Furthermore, OPN promotes BMSC migration by diminishing lamin A/C expression and decreasing nuclear stiffness via the FAK-ERK1/2 signaling pathway. This study provides strong evidence for the role of nuclear mechanics in BMSC migration as well as new insight into the molecular mechanisms of OPN-promoted BMSC migration.

Dual roles for bone marrow-derived Sca-1 cells in cardiac function

Recruitment of stem cells from the bone marrow (BM) is an important aspect of cardiac healing that becomes inefficient with age. We investigated the role of young stem cell antigen 1 (Sca-1)-positive BM cells on the aged heart by microarray analysis after BM reconstitution. Sca-1⁺ and Sca-1^- BM cells from young green fluorescent protein (GFP)-positive mice were used to reconstitute the BM of aged mice. Myocardial infarction (MI) was induced 3 mo later. GFP⁺ cells were more abundant in the BM, blood, and heart of Sca-1⁺ mice, which corresponded to preserved cardiac function after MI. At baseline, Sca-1⁺ BM reconstitution increased cardiac expression of serum response factor, vascular endothelial growth factor A, and myogenic genes, but reduced the expression of Il-1β. After MI, inflammation was identified as a key difference between Sca-1^- and Sca-1⁺ groups, as cytokine expression and cell surface markers associated with inflammatory cells were up-regulated with Sca-1⁺ reconstitution. Mac-3 and F4/80 staining showed that the postinfarction heart was composed of a mixture of GFP⁺ (donor) macrophages, GFP^- (host) macrophages, and GFP⁺ cells that did not contribute to the macrophage population. This study demonstrates that Sca-1⁺ BM cells regulate cardiac healing though an acute inflammatory response and also before injury by stimulating formation of a beneficial cardiac niche.-Tobin, S. W., Li, S.-H., Li, J., Wu, J., Yeganeh, A., Yu, P., Weisel, R. D., Li, R.-K. Dual roles for bone marrow-derived Sca-1 cells in cardiac function.

Triiodothyronine promotes the proliferation of epicardial progenitor cells through the MAPK/ERK pathway

Thyroid hormone has important functions in the development and physiological function of the heart. The aim of this study was to determine whether 3,5,3'-Triiodothyronine (T3) can promote the proliferation of epicardial progenitor cells (EPCs) and to investigate the potential underlying mechanism. Our results showed that T3 significantly promoted the proliferation of EPCs in a concentration- and time-dependent manner. The thyroid hormone nuclear receptor inhibitor bisphenol A (100 μmol/L) did not affect T3's ability to induce proliferation. Further studies showed that the mRNA expression levels of mitogen-activated protein kinase 1 (MAPK1), MAPK3, and Ki67 in EPCs in the T3 group (10 nmol/L) increased 2.9-, 3-, and 4.1-fold, respectively, compared with those in the control group (P < 0.05). In addition, the mRNA expression of the cell cycle protein cyclin D1 in the T3 group increased approximately 2-fold compared with the control group (P < 0.05), and there were more EPCs in the S phase of the cell cycle (20.6% vs. 12.0%, P < 0.05). The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway inhibitor U0126 (10 μmol/L) significantly inhibited the ability of T3 to promote the proliferation of EPCs and to alter cell cycle progression. This study suggested that T3 significantly promotes the proliferation of EPCs, and this effect may be achieved through activation of the MAPK/ERK signaling pathway.

Cell Surface Nano-modulation for Non-invasive in vivo Near-IR Stem Cell Monitoring

A stem cell tracking system is in high demand for the determination of cell destinations and for the validation of cell therapeutic efficacy in regenerative transplantation. To date, near-infrared (NIR) imaging technology has received considerable attention in cell behavior monitoring, owing to its patient compatibility, easy accessibility and cost effectiveness. Conventionally, in vivo cell tracking has been visualized by direct in-cell staining with NIR, where it may be achieved by complicated genetic engineering. Such genetic amendment techniques have suffered from serious challenges, which can destroy a cell's metabolism and can accidentally incur unexpected carcinoma. Herein we demonstrate a novel cell nano-modulation method for noninvasive stem cell monitoring. It is simply achieved by conjugating stem cells with lipid-supported, NIR-tagged, polymeric nanoparticles. These engineered cells, which are designated as NIR-labeled light-emitting stem cells (LESCs), maintain their biochemical functionality (i.e., differentiation, quantum efficacy, etc.) even after conjugation. LESCs were used for in situ stem cell monitoring at inoculation sites. It is speculated that the LESC technique could provide a new preparative methodology for in vivo cell tracking in advanced diagnostic medicine, where cell behavior is a critical issue.

Pivotal Cytoprotective Mediators and Promising Therapeutic Strategies for Endothelial Progenitor Cell-Based Cardiovascular Regeneration

Cardiovascular diseases (CVDs), including atherosclerosis, stroke, and myocardial infarction, is a major cause of death worldwide. In aspects of cell therapy against CVD, it is generally accepted that endothelial progenitor cells (EPCs) are potent neovascular modulators in ischemic tissues. In response to ischemic injury signals, EPCs located in a bone marrow niche migrate to injury sites and form new vessels by secreting various vasculogenic factors including VEGF, SDF-1, and FGF, as well as by directly differentiating into endothelial cells. Nonetheless, in ischemic tissues, most of engrafted EPCs do not survive under harsh ischemic conditions and nutrient depletion. Therefore, an understanding of diverse EPC-related cytoprotective mediators underlying EPC homeostasis in ischemic tissues may help to overcome current obstacles for EPC-mediated cell therapy for CVDs. Additionally, to enhance EPC's functional capacity at ischemic sites, multiple strategies for cell survival should be considered, that is, preconditioning of EPCs with function-targeting drugs including natural compounds and hormones, virus mediated genetic modification, combined therapy with other stem/progenitor cells, and conglomeration with biomaterials. In this review, we discuss multiple cytoprotective mediators of EPC-based cardiovascular repair and propose promising therapeutic strategies for the treatment of CVDs.

Isolation, Characterization, and Establishment of Spontaneously Immortalized Cell Line HRPE-2S With Stem Cell Properties

The retinal pigment epithelium is a monolayer of highly specialized pigmented cells located between the neural retina and the Bruch's membrane of the choroid. RPE cells play a crucial role in the maintenance and function of the underlying photoreceptors. This study introduces a spontaneously arising human retinal pigment epithelial cell line, HRPE-2S, which was isolated from primary RPE cell culture of 2 days old male donor. We characterized morphology and functional properties of the new cell line. The immortalized cell line was maintained in culture for more than 70 passages and 240 divisions. The average doubling time of the cells was approximately 22 h and got freezed at 26th passage. The cell line expressed RPE-specific markers RPE65 and cell junction protein ZO1 as an epithelial cell marker. It also expressed CHX10, PAX6, Nestin, SOX2 as stem and retinal progenitor cell markers. Ki67 as a marker of cell proliferation was expressed in all HRPE-2S cells. It represented typical epithelial cobblestone morphology and did not phenotypically change through several passages. Stem cell-like aggregations (neurospheres) were observed in SEM microscopy. The cells represented high mitotic index. They could be viable under hypoxic conditions and serum deprivation. According to functional studies, the cell line exhibited stem cell-like behaviors with particular emphasis on its self-renewal capacity. LDH isoenzymes expression pattern confirmed the same cellular source for both of the HRPE-2S cells and primary RPE cells. Characteristics of HRPE-2S cells promise it as an in vitro model for RPE stem cell-based researches. J. Cell. Physiol. 232: 2626-2640, 2017. © 2016 Wiley Periodicals, Inc.

Stem/progenitor cells and obstructive sleep apnea syndrome - new insights for clinical applications

Obstructive sleep apnea syndrome (OSAS) is a widespread disorder, characterized by recurrent upper airway obstruction during sleep, mostly as a result of complete or partial pharyngeal obstruction. Due to the occurrence of frequent and regular hypoxic events, patients with OSAS are at increased risk of cardiovascular disease, stroke, metabolic disorders, occupational errors, motor vehicle accidents and even death. Thus, OSAS has severe consequences and represents a significant economic burden. However, some of the consequences, as well as their costs can be reduced with appropriate detection and treatment. In this context, the recent advances that were made in stem cell biology knowledge and stem cell - based technologies hold a great promise for various medical conditions, including respiratory diseases. However, the investigation of the role of stem cells in OSAS is still recent and rather limited, requiring further studies, both in animal models and humans. The goal of this review is to summarize the current state of knowledge regarding both lung resident as well as circulating stem/progenitor cells and discuss existing controversies in the field in order to identify future research directions for clinical applications in OSAS. Also, the paper highlights the requisite for inter-institutional, multi-disciplinary research collaborations in order to achieve breakthrough results in the field.

Recruiting endogenous stem cells: a novel therapeutic approach for erectile dysfunction

Transplanted stem cells (SCs), owing to their regenerative capacity, represent one of the most promising methods to restore erectile dysfunction (ED). However, insufficient source, invasive procedures, ethical and regulatory issues hamper their use in clinical applications. The endogenous SCs/progenitor cells resident in organ and tissues play critical roles for organogenesis during development and for tissue homeostasis in adulthood. Even without any therapeutic intervention, human body has a robust self-healing capability to repair the damaged tissues or organs. Therefore, SCs-for-ED therapy should not be limited to a supply-side approach. The resident endogenous SCs existing in patients could also be a potential target for ED therapy. The aim of this review was to summarize contemporary evidence regarding: (1) SC niche and SC biological features in vitro; (2) localization and mobilization of endogenous SCs; (3) existing evidence of penile endogenous SCs and their possible mode of mobilization. We performed a search on PubMed for articles related to these aspects in a wide range of basic studies. Together, numerous evidences hold the promise that endogenous SCs would be a novel therapeutic approach for the therapy of ED.

Controlled Release of Collagen-Binding SDF-1α Improves Cardiac Function after Myocardial Infarction by Recruiting Endogenous Stem Cells

Stromal cell-derived factor-1α (SDF-1α) is a well-characterized chemokine that mobilizes stem cells homing to the ischemic heart, which is beneficial for cardiac regeneration. However, clinically administered native SDF-1α diffuses quickly, thus decreasing its local concentration, and results in side effects. Thus, a controlled release system for SDF-1α is required to produce an effective local concentration in the ischemic heart. In this study, we developed a recombinant chemokine, consisting of SDF-1α and a collagen-binding domain, which retains both the SDF-1α and collagen-binding activity (CBD-SDF-1α). In an in vitro assay, CBD-SDF-1α could specifically bind to a collagen gel and achieve sustained release. An intramyocardial injection of CBD-SDF-1α after acute myocardial infarction demonstrated that the protein was largely tethered in the ischemic area and that controlled release had been achieved. Furthermore, CBD-SDF-1α enhanced the recruitment of c-kit positive (c-kit⁺) stem cells, increased capillary density and improved cardiac function, whereas NAT-SDF-1α had no such beneficial effects. Our findings demonstrate that CBD-SDF-1α can specifically bind to collagen and achieve controlled release both in vitro and in vivo. Local delivery of this protein could mobilize endogenous stem cells homing to the ischemic heart and improve cardiac function after myocardial infarction.

Position Paper of the European Society of Cardiology Working Group Cellular Biology of the Heart: cell-based therapies for myocardial repair and regeneration in ischemic heart disease and heart failure

Despite improvements in modern cardiovascular therapy, the morbidity and mortality of ischaemic heart disease (IHD) and heart failure (HF) remain significant in Europe and worldwide. Patients with IHD may benefit from therapies that would accelerate natural processes of postnatal collateral vessel formation and/or muscle regeneration. Here, we discuss the use of cells in the context of heart repair, and the most relevant results and current limitations from clinical trials using cell-based therapies to treat IHD and HF. We identify and discuss promising potential new therapeutic strategies that include ex vivo cell-mediated gene therapy, the use of biomaterials and cell-free therapies aimed at increasing the success rates of therapy for IHD and HF. The overall aim of this Position Paper of the ESC Working Group Cellular Biology of the Heart is to provide recommendations on how to improve the therapeutic application of cell-based therapies for cardiac regeneration and repair.

Insight on stem cell preconditioning and instructive biomaterials to enhance cell adhesion, retention, and engraftment for tissue repair

Stem cells are a promising solution for the treatment of a variety of diseases. However, the limited survival and engraftment of transplanted cells due to a hostile ischemic environment is a bottleneck for effective utilization and commercialization. Within this environment, the majority of transplanted cells undergo apoptosis prior to participating in lineage differentiation and cellular integration. Therefore, in order to maximize the clinical utility of stem/progenitor cells, strategies must be employed to increase their adhesion, retention, and engraftment in vivo. Here, we reviewed key strategies that are being adopted to enhance the survival, retention, and engraftment of transplanted stem cells through the manipulation of both the stem cells and the surrounding environment. We describe how preconditioning of cells or cell manipulations strategies can enhance stem cell survival and engraftment after transplantation. We also discuss how biomaterials can enhance the function of stem cells for effective tissue regeneration. Biomaterials can incorporate or mimic extracellular function (ECM) function and enhance survival or differentiation of transplanted cells in vivo. Biomaterials can also promote angiogenesis, enhance engraftment and differentiation, and accelerate electromechanical integration of transplanted stem cells. Insight gained from this review may direct the development of future investigations and clinical trials.

Macrophage precursor cells from the left atrial appendage of the heart spontaneously reprogram into a C-kit+/CD45- stem cell-like phenotype

BACKGROUND

The developmental origin of the c-kit expressing progenitor cell pool in the adult heart has remained elusive. Recently, it has been discovered that the injured heart is enriched with c-kit(+) cells, which also express the hematopoietic marker CD45.

METHODS AND RESULTS

In this study, we characterize the phenotype and transcriptome of the c-kit+/CD45+/CD11b+/Flk-1+/Sca-1±(B-type) cell population, originating from the left atrial appendage. These cells are defined as cardiac macrophage progenitors. We also demonstrate that the CD45+ progenitor cell population activates heart development, neural crest and pluripotency-associated pathways in vitro, in conjunction with CD45 down-regulation, and acquire a c-kit+/CD45-/CD11b-/Flk-1-/Sca-1+ (A-type) phenotype through cell fusion and asymmetric division. This putative spontaneous reprogramming evolves into a highly proliferative, partially myogenic phenotype (C-type).

CONCLUSIONS

Our data suggests that A-type cells and cardiac macrophage precursor cells (B-type) have a common lineage origin, possibly resolving some current conundrums in the field of cardiac regeneration.

Stromal cell-derived factor-1-directed bone marrow mesenchymal stem cell migration in response to inflammatory and/or hypoxic stimuli

Directing cell trafficking toward a target site of interest is critical for advancing stem cell therapy in clinical theranostic applications. In this study, we investigated the effects of inflammatory and/or hypoxic stimuli on the migration of bone marrow mesenchymal stem cells (BMMSCs) during in vitro culture and after in vivo implantation. Using tablet scratch experiments and observations from a transwell system, we found that both inflammatory and hypoxic stimuli significantly enhanced cell migration. However, the combination of inflammatory and hypoxic stimuli did not result in a synergistic effect. The presence of stromal cell-derived factor-1 (SDF-1) significantly enhanced cell migration irrespective of the incubation conditions, and these positive effects could be blocked by treatment with AMD3100. Based on a time course experiment, we found that preconditioning cells with either inflammatory or hypoxic stimuli for 24 h or with both stimuli for 12 h led to high levels of chemokine receptor type 4 (CXCR4) expression. In vivo studies further demonstrated that pretreatment of BMMSCs with inflammatory and/or hypoxic stimuli resulted in an increased number of systemically injected cells migrating toward skin injuries, and local SDF-1 administration significantly increased cell migration. These findings suggest that in vitro control of either inflammatory or hypoxic stimuli has significant potential to enhance SDF-1-directed BMMSC migration via the upregulation of CXCR4 expression. Although combining the stimuli did not necessarily lead to a synergistic effect, the potential to reduce the dose and time required for cell preconditioning indicates that combinations of various strategies warrant further exploration.

Quantitative evaluation of the transplanted lin(-) hematopoietic cell migration kinetics

Stem cells take part in organogenesis, cell maturation and injury repair. The migration is necessary for each of these functions to occur. The aim of this study was to investigate the kinetics of transplanted hematopoietic lin(-) cell population (which consists mainly of the stem and progenitor cells) in BALB/c mouse contact hypersensitivity model and quantify the migration to the site of inflammation in the affected foot and other healthy organs. Quantitative analysis was carried out with the real-time polymerase chain reaction method. Spleen, kidney, bone marrow, lung, liver, damaged and healthy foot tissue samples at different time points were collected for analysis. The quantitative data normalization was performed according to the comparative quantification method. The analysis of foot samples shows the significant migration of transplanted cells to the recipient mice affected foot. The quantity was more than 1000 times higher, as compared with that of the untreated foot. Due to the inflammation, the number of donor origin cells migrating to the lungs, liver, spleen and bone marrow was found to be decreased. Our data shows that transplanted cells selectively migrated into the inflammation areas of the foot edema. Also, the inflammation caused a secondary migration in ectopic spleen of hematopoietic stem cell niches and re-homing from the spleen to the bone marrow took place.

PDL regeneration via cell homing in delayed replantation of avulsed teeth

Background

This study was aimed to investigate whether regeneration of periodontal ligament (PDL) like tissue could be promoted by stromal cell-derived factor-1 (SDF1) and bone morphogenetic protein-7 (BMP7) induced cell homing in delayed replantation of avulsed teeth.

Methods

Canine mandibular premolar teeth were first extracted and air-dried for 2 h followed by complete detachment of their PDL tissues. The crown and pulp of the teeth were also removed. Twenty-four roots divided into two groups (n = 12/group) were used for the following in vivo transplantation. The roots of Group A were treated with 17 % EDTA for 24 h to achieve demineralization, and then coated with SDF1 and BMP7 supplemented collagen solution. The roots of Group B were similarly treated except being coated with a pristine collagen solution. The above roots were transplanted in the sockets that formed previously during tooth extraction. At 6 months’ post-operation, PDL-like tissue composed of spindle-shaped cells, capillaries and highly organized collagen fibers was observed in the interstitial space between the avulsed root surface and surrounding alveolar bone in Group A. The neo-fibers inserted deeply and perpendicularly into the cementum and adjacent bone. The periodontium-like characteristics of the neo-tissue was confirmed by immunohistochemical staining for collagen I, fibronectin and osteocalcin.

Results

A high incidence of PDL re-establishment as 42 % was achieved for samples of Group A. However, no PDL-like tissue was found but root ankylosis and replacement resorption as well as inflammatory resorption was observed in the replanted roots of Group B.

Conclusions

It can be confirmed that avulsed teeth could be successfully rescued even in delayed transplantation to avoid dentoalveolar ankylosis or replacement resorption via the current developed cell homing method.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0719-2) contains supplementary material, which is available to authorized users.

Transdifferentiation via transcription factors or microRNAs: Current status and perspective

Transdifferentiation as a new approach for obtaining the ideal cells for transplantation has gradually become a hot research topic. Compared with the induced pluripotent stem cells technique, transdifferentiation may have better efficiency and safety. Although the mechanism of transdifferentiation is still unknown, many studies have achieved transformation of one cell type to another through transcription factors or microRNA. The current major strategy for transdifferentiation is via transcription factors; however, there are some safety issues with the use of transcription factors. In contrast, microRNA as a novel tool for inducing transdifferentiation through post-transcriptional regulation may be more safe and efficient. In addition, the present transdifferentiation strategies involve obtaining the terminal cell directly, so the amount of cells produced may not be sufficient and they may have low capacity for cell immigration and integration. Therefore, an indirect transdifferentiation strategy for producing unipotent cells is ideal as it can preserve the proliferation capacity and differentiation pathway.

Roles of store-operated Ca2+ channels in regulating cell cycling and migration of human cardiac c-kit+ progenitor cells

Cardiac c-kit(+) progenitor cells are important for maintaining cardiac homeostasis and can potentially contribute to myocardial repair. However, cellular physiology of human cardiac c-kit(+) progenitor cells is not well understood. The present study investigates the functional store-operated Ca(2+) entry (SOCE) channels and the potential role in regulating cell cycling and migration using confocal microscopy, RT-PCR, Western blot, coimmunoprecipitation, cell proliferation, and migration assays. We found that SOCE channels mediated Ca(2+) influx, and TRPC1, STIM1, and Orai1 were involved in the formation of SOCE channels in human cardiac c-kit(+) progenitor cells. Silencing TRPC1, STIM1, or Orai1 with the corresponding siRNA significantly reduced the Ca(2+) signaling through SOCE channels, decreased cell proliferation and migration, and reduced expression of cyclin D1, cyclin E, and/or p-Akt. Our results demonstrate the novel information that Ca(2+) signaling through SOCE channels regulates cell cycling and migration via activating cyclin D1, cyclin E, and/or p-Akt in human cardiac c-kit(+) cells.

High Tibial Osteotomy in Combination With Chondrogenesis After Stem Cell Therapy: A Histologic Report of 8 Cases

PURPOSE

To histologically evaluate the quality of articular cartilage regeneration from the medial compartment after arthroscopic subchondral drilling followed by postoperative intra-articular injections of autologous peripheral blood stem cells (PBSCs) and hyaluronic acid with concomitant medial open-wedge high tibial osteotomy (HTO) in patients with varus deformity of the knee joint.

METHODS

Eight patients with varus deformity of the knee joint underwent arthroscopic subchondral drilling of International Cartilage Repair Society (ICRS) grade 4 bone-on-bone lesions of the medial compartment with concomitant HTO. These patients were part of a larger pilot study in which 18 patients underwent the same procedure. PBSCs were harvested and cryopreserved preoperatively. At 1 week after surgery, 8 mL of PBSCs was mixed with 2 mL of hyaluronic acid and injected intra-articularly into the knee joint; this was repeated once a week for 5 consecutive weeks. Three additional intra-articular injections were administered weekly at intervals of 6, 12, and 18 months postoperatively. Informed consent was obtained at the time of hardware removal for opportunistic second-look arthroscopy and chondral biopsy. Biopsy specimens were stained with H&E, safranin O, and immunohistochemical staining for type I and II collagen. Specimens were graded using the 14 components of the ICRS Visual Assessment Scale II, and a total score was obtained.

RESULTS

Second-look arthroscopy showed satisfactory healing of the regenerated cartilage. Histologic analysis showed significant amounts of proteoglycan and type II collagen. The total ICRS Visual Assessment Scale II histologic scores comparing the regenerated articular cartilage (mean, 1,274) with normal articular cartilage (mean, 1,340) indicated that the repair cartilage score approached 95% of the normal articular cartilage score. There were no infections, delayed unions, or nonunions.

CONCLUSIONS

Chondrogenesis with stem cells in combination with medial open-wedge HTO for varus deformity correction of the knee joint regenerates cartilage that closely resembles the native articular cartilage.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Stromal Cell-Derived Factor-1α Plays a Crucial Role Based on Neuroprotective Role in Neonatal Brain Injury in Rats

Owing to progress in perinatal medicine, the survival of preterm newborns has markedly increased. However, the incidence of cerebral palsy has risen in association with increased preterm birth. Cerebral palsy is largely caused by cerebral hypoxic ischemia (HI), for which there are no effective medical treatments. We evaluated the effects of stromal cell-derived factor-1α (SDF-1α) on neonatal brain damage in rats. Left common carotid (LCC) arteries of seven-day-old Wistar rat pups were ligated, and animals were exposed to hypoxic gas to cause cerebral HI. Behavioral tests revealed that the memory and spatial perception abilities were disturbed in HI animals, and that SDF-1α treatment improved these cognitive functions. Motor coordination was also impaired after HI but was unimproved by SDF-1α treatment. SDF-1α reduced intracranial inflammation and induced cerebral remyelination, as indicated by the immunohistochemistry results. These data suggest that SDF-1α specifically influences spatial perception abilities in neonatal HI encephalopathy.

Cancer stem cells: a challenging paradigm for designing targeted drug therapies

Despite earlier controversies about their role and existence within tumors, cancer stem cells (CSCs) are now emerging as a plausible target for new drug discovery. Research and development (R&D) efforts are being directed against key gene(s) driving initiation, growth, and metastatic pathways in CSCs and the tumor microenvironment (TME). However, the niche signals that enable these pluripotent CSCs to evade radio- and chemotherapy, and to travel to secondary tissues remain enigmatic. Small-molecule drugs, biologics, miRNA, RNA interference (RNAi), and vaccines, among others, are under active investigation. Here, we examine the feasibility of leveraging current knowhow of the molecular biology of CSCs and their cellular milieu to design futuristic, targeted drugs with potentially lower toxicity that can override the multiple drug-resistance issues currently observed with existing therapeutics.