Updates on stem cells and their applications in regenerative medicine

Scaffold-free 3D culture systems for stem cell-based tissue regeneration

Recent advances in scaffold-free three-dimensional (3D) culture methods have significantly enhanced the potential of stem cell-based therapies in regenerative medicine. This cutting-edge technology circumvents the use of exogenous biomaterial and prevents its associated complications. The 3D culture system preserves crucial intercellular interactions and extracellular matrix support, closely mimicking natural biological niches. Therefore, stem cells cultured in 3D formats exhibit distinct characteristics, showcasing their capabilities in promoting angiogenesis and immunomodulation. This review aims to elucidate foundational technologies and recent breakthroughs in 3D scaffold-free stem cell engineering, offering comprehensive guidance for researchers to advance this technology across various clinical applications. We first introduce the various sources of stem cells and provide a comparative analysis of two-dimensional (2D) and 3D culture systems. Given the advantages of 3D culture systems, we delve into the specific fabrication and harvesting techniques for cell sheets and spheroids. Furthermore, we explore their applications in pre-clinical studies, particularly in large animal models and clinical trials. We also discuss multidisciplinary strategies to overcome existing limitations such as insufficient efficacy, hostile microenvironments, and the need for scalability and standardization of stem cell-based products.

Exploring the dichotomy of the mesenchymal stem cell secretome: Implications for tumor modulation via cell-signaling pathways

Current cancer therapeutic strategies for the treatment of cancer are often unsuccessful due to unwanted side effects and drug resistance. Therefore, the design and development of potent, new anticancer platforms, such as stem-cell treatments, have attracted much attention. Distinctive biological properties of stem cells include their capacity to secrete bioactive factors, their limited immunogenicity, and their capacity for renewing themselves. Mesenchymal stem cells (MSCs) are one of several kinds of stem cells that are conveniently extracted and are able to be cultivated in vitro utilizing various sources. The secretome of stem cells contains many trophic factors, including cytokines, chemokines, growth factors, and microRNA molecules that can either promote or inhibit the formation of tumors, based on the cell environment. In the current review, we focused on the secretome of mesenchymal stem cells. These stem cells act as a double-edged sword in the regulation of cell signal transduction pathways in that they can either suppress or promote tumors.

Exploring the Potential of Saphenous Vein Grafts Ex Vivo: A Model for Intimal Hyperplasia and Re-Endothelialization

Coronary artery bypass grafting (CABG) utilizing saphenous vein grafts (SVGs) stands as a fundamental approach to surgically treating coronary artery disease. However, the long-term success of CABG is often compromised by the development of intimal hyperplasia (IH) and subsequent graft failure. Understanding the mechanisms underlying this pathophysiology is crucial for improving graft patency and patient outcomes. Objectives: This study aims to explore the potential of an ex vivo model utilizing SVG to investigate IH and re-endothelialization. Methods: A thorough histological examination of 15 surplus SVG procured from CABG procedures at Hospital Canselor Tuanku Muhriz, Malaysia, was conducted to establish their baseline characteristics. Results: SVGs exhibited a mean diameter of 2.65 ± 0.93 mm with pre-existing IH averaging 0.42 ± 0.13 mm in thickness, alongside an observable lack of luminal endothelial cell lining. Analysis of extracellular matrix components, including collagen, elastin, and glycosaminoglycans, at baseline and after 7 days of ex vivo culture revealed no significant changes in collagen but demonstrated increased percentages of elastin and glycosaminoglycans. Despite unsuccessful attempts at re-endothelialization with blood outgrowth endothelial cells, the established ex vivo SVG IH model underscores the multifaceted nature of graft functionality and patency, characterized by IH presence, endothelial impairment, and extracellular matrix alterations post-CABG. Conclusions: The optimized ex vivo IH model provides a valuable platform for delving into the underlying mechanisms of IH formation and re-endothelialization of SVG. Further refinements are warranted, yet this model holds promise for future research aimed at enhancing graft durability and outcomes for CAD patients undergoing CABG.

A novel tissue-engineered corneal epithelium based on ultra-thin amniotic membrane and mesenchymal stem cells

Currently, in vitro cultured corneal epithelial transplantation is effective in treating limbal stem cell dysfunction (LSCD). Selecting carriers is crucial for constructing the corneal epithelium through tissue engineering. In this study, the traditional amniotic membrane (AM) was modified, and mesenchymal stem cells (MSCs) were inoculated into the ultra-thin amniotic membrane (UAM) stroma to construct a novel UAM-MSC tissue-engineered corneal epithelial carrier, that could effectively simulate the limbal stem cells (LSCs) microenvironment. The structure of different carriers cultured tissue-engineered corneal epithelium and the managed rabbit LSCD model corneas were observed through hematoxylin-eosin staining. Cell phenotypes were evaluated through fluorescence staining, Western blotting, and RT-qPCR. Additionally, cell junction genes and expression markers related to anti-neovascularization were evaluated using RT-qPCR. Corneal epithelium cell junctions were observed via an electron microscope. The tissue-engineered corneal epithelium culture medium was analyzed through mass spectrometry. Tissue-engineered corneal epithelial cells expanded by LSCs on UAM-MSCs had good transparency. Simultaneously, progenitor cell (K14, PNCA, p63) and corneal epithelial (PAX6) gene expression in tissue-engineered corneal epithelium constructed using UAM-MSCs was higher than that in corneal epithelial cells amplified by UAM and de-epithelialized amniotic membrane. Electron microscopy revealed that corneal epithelial cells grafted with UAM-MSCs were closely connected. In conclusion, the UAM-MSCs vector we constructed could better simulate the limbal microenvironment; the cultured tissue-engineered corneal epithelium had better transparency, anti-neovascularization properties, closer intercellular connections, and closer resemblance to the natural corneal epithelial tissue phenotype.

Advances of Schwann cells in peripheral nerve regeneration: From mechanism to cell therapy

Peripheral nerve injuries (PNIs) frequently occur due to various factors, including mechanical trauma such as accidents or tool-related incidents, as well as complications arising from diseases like tumor resection. These injuries frequently result in persistent numbness, impaired motor and sensory functions, neuropathic pain, or even paralysis, which can impose a significant financial burden on patients due to outcomes that often fall short of expectations. The most frequently employed clinical treatment for PNIs involves either direct sutures of the severed ends or bridging the proximal and distal stumps using autologous nerve grafts. However, autologous nerve transplantation may result in sensory and motor functional loss at the donor site, as well as neuroma formation and scarring. Transplantation of Schwann cells/Schwann cell-like cells has emerged as a promising cellular therapy to reconstruct the microenvironment and facilitate peripheral nerve regeneration. In this review, we summarize the role of Schwann cells and recent advances in Schwann cell therapy in peripheral nerve regeneration. We summarize current techniques used in cell therapy, including cell injection, 3D-printed scaffolds for cell delivery, cell encapsulation techniques, as well as the cell types employed in experiments, experimental models, and research findings. At the end of the paper, we summarize the challenges and advantages of various cells (including ESCs, iPSCs, and BMSCs) in clinical cell therapy. Our goal is to provide the theoretical and experimental basis for future treatments targeting peripheral nerves, highlighting the potential of cell therapy and tissue engineering as invaluable resources for promoting nerve regeneration.

Introduction to stem cell biology and its role in treating neurologic disorders

Regenerative medicine is an emerging and rapidly evolving field of research and therapeutics aimed to restore, maintain, and improve body functions. In the adult mammalian brain, very few neurons, if any, are generated after disease onset or an injury, and its ability to self-repair is therefore limited. Replacing neurons that are lost during neurodegenerative diseases or due to injury therefore represents one of the major challenges to modern medicine. In this introductory chapter, we describe the basic biology of stem cells and outline how stem cells and cell reprogramming can be utilized to create new neurons for therapeutic purposes that are discussed in detail in other chapters in this handbook.

Mechanisms of Wharton's Jelly-derived MSCs in enhancing peripheral nerve regeneration

Warton's jelly-derived Mesenchymal stem cells (WJ-MSCs) play key roles in improving nerve regeneration in acellular nerve grafts (ANGs); however, the mechanism of WJ-MSCs-related nerve regeneration remains unclear. This study investigated how WJ-MSCs contribute to peripheral nerve regeneration by examining immunomodulatory and paracrine effects, and differentiation potential. To this end, WJ-MSCs were isolated from umbilical cords, and ANGs (control) or WJ-MSCs-loaded ANGs (WJ-MSCs group) were transplanted in injury animal model. Functional recovery was evaluated by ankle angle and tetanic force measurements up to 16 weeks post-surgery. Tissue biopsies at 3, 7, and 14 days post-transplantation were used to analyze macrophage markers and interleukin (IL) levels, paracrine effects, and MSC differentiation potential by quantitative real-time polymerase chain reaction (RT-qPCR) and immunofluorescence staining. The WJ-MSCs group showed significantly higher ankle angle at 4 weeks and higher isometric tetanic force at 16 weeks, and increased expression of CD206 and IL10 at 7 or 14 days than the control group. Increased levels of neurotrophic and vascular growth factors were observed at 14 days. The WJ-MSCs group showed higher expression levels of S100β; however, the co-staining of human nuclei was faint. This study demonstrates that WJ-MSCs' immunomodulation and paracrine actions contribute to peripheral nerve regeneration more than their differentiation potential.

Bone Tissue Engineering (BTE) of the Craniofacial Skeleton, Part I: Evolution and Optimization of 3D-Printed Scaffolds for Repair of Defects

Bone tissue regeneration is a complex process that proceeds along the well-established wound healing pathway of hemostasis, inflammation, proliferation, and remodeling. Recently, tissue engineering efforts have focused on the application of biological and technological principles for the development of soft and hard tissue substitutes. Aim is directed towards boosting pathways of the healing process to restore form and function of tissue deficits. Continued development of synthetic scaffolds, cell therapies, and signaling biomolecules seeks to minimize the need for autografting. Despite being the current gold standard treatment, it is limited by donor sites' size and shape, as well as donor site morbidity. Since the advent of computer-aided design/computer-aided manufacturing (CAD/CAM) and additive manufacturing (AM) techniques (3D printing), bioengineering has expanded markedly while continuing to present innovative approaches to oral and craniofacial skeletal reconstruction. Prime examples include customizable, high-strength, load bearing, bioactive ceramic scaffolds. Porous macro- and micro-architecture along with the surface topography of 3D printed scaffolds favors osteoconduction and vascular in-growth, as well as the incorporation of stem and/or other osteoprogenitor cells and growth factors. This includes platelet concentrates (PCs), bone morphogenetic proteins (BMPs), and some pharmacological agents, such as dipyridamole (DIPY), an adenosine A 2A receptor indirect agonist that enhances osteogenic and osteoinductive capacity, thus improving bone formation. This two-part review commences by presenting current biological and engineering principles of bone regeneration utilized to produce 3D-printed ceramic scaffolds with the goal to create a viable alternative to autografts for craniofacial skeleton reconstruction. Part II comprehensively examines recent preclinical data to elucidate the potential clinical translation of such 3D-printed ceramic scaffolds.

Translational Research Techniques for the Facial Plastic Surgeon: An Overview

The field of facial plastic and reconstructive surgery (FPRS) is an incredibly diverse, multispecialty field that seeks innovative and novel solutions for the management of physical defects on the head and neck. To aid in the advancement of medical and surgical treatments for these defects, there has been a recent emphasis on the importance of translational research. With recent technological advancements, there are now a myriad of research techniques that are widely accessible for physician and scientist use in translational research. Such techniques include integrated multiomics, advanced cell culture and microfluidic tissue models, established animal models, and emerging computer models generated using bioinformatics. This study discusses these various research techniques and how they have and can be used for research in the context of various important diseases within the field of FPRS.

Application of Adipose-Tissue Derived Products for Burn Wound Healing

Burn injuries are a significant global health concern, leading to high morbidity and mortality. Deep burn injuries often result in delayed healing and scar formation, necessitating effective treatment options. Regenerative medicine, particularly cell therapy using adipose-derived stem cells (ASCs), has emerged as a promising approach to improving burn wound healing and reducing scarring. Both in vitro and preclinical studies have demonstrated the efficacy of ASCs and the stromal vascular fraction (SVF) in addressing burn wounds. The application of ASCs for burn healing has been studied in various forms, including autologous or allogeneic cells delivered in suspension or within scaffolds in animal burn models. Additionally, ASC-derived non-cellular components, such as conditioned media or exosomes have shown promise. Injection of ASCs and SVF at burn sites have been demonstrated to enhance wound healing by reducing inflammation and promoting angiogenesis, epithelialization, and granulation tissue formation through their paracrine secretome. This review discusses the applications of adipose tissue derivatives in burn injury treatment, encompassing ASC transplantation, as well as the utilization of non-cellular components utilization for therapeutic benefits. The application of ASCs in burn healing in the future will require addressing donor variability, safety, and efficacy for successful clinical application.

Mesenchymal Stem Cells and Exosomes: A Novel Therapeutic Approach for Corneal Diseases

The cornea, with its delicate structure, is vulnerable to damage from physical, chemical, and genetic factors. Corneal transplantation, including penetrating and lamellar keratoplasties, can restore the functions of the cornea in cases of severe damage. However, the process of corneal transplantation presents considerable obstacles, including a shortage of available donors, the risk of severe graft rejection, and potentially life-threatening complications. Over the past few decades, mesenchymal stem cell (MSC) therapy has become a novel alternative approach to corneal regeneration. Numerous studies have demonstrated the potential of MSCs to differentiate into different corneal cell types, such as keratocytes, epithelial cells, and endothelial cells. MSCs are considered a suitable candidate for corneal regeneration because of their promising therapeutic perspective and beneficial properties. MSCs compromise unique immunomodulation, anti-angiogenesis, and anti-inflammatory properties and secrete various growth factors, thus promoting corneal reconstruction. These effects in corneal engineering are mediated by MSCs differentiating into different lineages and paracrine action via exosomes. Early studies have proven the roles of MSC-derived exosomes in corneal regeneration by reducing inflammation, inhibiting neovascularization, and angiogenesis, and by promoting cell proliferation. This review highlights the contribution of MSCs and MSC-derived exosomes, their current usage status to overcome corneal disease, and their potential to restore different corneal layers as novel therapeutic agents. It also discusses feasible future possibilities, applications, challenges, and opportunities for future research in this field.

A Simplified and Effective Approach for the Isolation of Small Pluripotent Stem Cells Derived from Human Peripheral Blood

Pluripotent stem cells are key players in regenerative medicine. Embryonic pluripotent stem cells, despite their significant advantages, are associated with limitations such as their inadequate availability and the ethical dilemmas in their isolation and clinical use. The discovery of very small embryonic-like (VSEL) stem cells addressed the aforementioned limitations, but their isolation technique remains a challenge due to their small cell size and their efficiency in isolation. Here, we report a simplified and effective approach for the isolation of small pluripotent stem cells derived from human peripheral blood. Our approach results in a high yield of small blood stem cell (SBSC) population, which expresses pluripotent embryonic markers (e.g., Nanog, SSEA-3) and the Yamanaka factors. Further, a fraction of SBSCs also co-express hematopoietic markers (e.g., CD45 and CD90) and/or mesenchymal markers (e.g., CD29, CD105 and PTH1R), suggesting a mixed stem cell population. Finally, quantitative proteomic profiling reveals that SBSCs contain various stem cell markers (CD9, ITGA6, MAPK1, MTHFD1, STAT3, HSPB1, HSPA4), and Transcription reg complex factors (e.g., STAT5B, PDLIM1, ANXA2, ATF6, CAMK1). In conclusion, we present a novel, simplified and effective isolating process that yields an abundant population of small-sized cells with characteristics of pluripotency from human peripheral blood.

Nanomedicines Targeting Glioma Stem Cells

Glioblastoma (GBM), classified as a grade IV glioma, is a rapidly growing, aggressive, and most commonly occurring tumor of the central nervous system. Despite the therapeutic advances, it carries an ominous prognosis, with a median survival of 14.6 months after diagnosis. Accumulating evidence suggests that cancer stem cells in GBM, termed glioma stem cells (GSCs), play a crucial role in tumor propagation, treatment resistance, and tumor recurrence. GSCs, possessing the capacity for self-renewal and multilineage differentiation, are responsible for tumor growth and heterogeneity, leading to primary obstacles to current cancer therapy. In this respect, increasing efforts have been devoted to the development of anti-GSC strategies based on targeting GSC surface markers, blockage of essential signaling pathways of GSCs, and manipulating the tumor microenvironment (GSC niches). In this review, we will discuss the research knowledge regarding GSC-based therapy and the underlying mechanisms for the treatment of GBM. Given the rapid progression in nanotechnology, innovative nanomedicines developed for GSC targeting will also be highlighted from the perspective of rationale, advantages, and limitations. The goal of this review is to provide broader understanding and key considerations toward the future direction of GSC-based nanotheranostics to fight against GBM.

Application of Stem Cell in Human Erectile Dysfunction - A Systematic Review

Introduction

Erectile dysfunction is a health problem that arises from various conditions and causes an impaired quality of life with a significant health burden. Regenerative and stem cell therapies are some of the potential treatments for erectile dysfunction. This study aimed to review the available information in the literature regarding the use of stem cells in the treatment of erectile dysfunction.

Methods

This study is a systematic review conducted based on the PubMed, Google Scholar, Cochrane, and DOAJ databases. Literature searching was conducted in English and included articles from 2000 to 2020.

Results

The result was a total of 318 articles. Following the elimination process, 9 articles remained in the final analysis. The analyzed studies included 164 patients with erectile dysfunction with various medical conditions. Several stem cell types have been used for treating erectile dysfunction, including mesenchymal stem cell, placental matrix-derived stem cell, mesenchymal stem cell-derived exosome, adipose-derived stem cell, bone marrow-derived mononuclear stem cell, and umbilical cord blood stem cell. Generally, stem cell therapy showed a good efficacy and safety profile, although not enough studies on the protocol, dosage, and mechanism of action.

Conclusion

Stem cell therapy has a good therapeutic potential in erectile dysfunction, the available data from the literature could be the base of usage of stem cells in the treatment of erectile dysfunction although need more research for broader usage.

LncRNA MALAT1 from human adipose-derived stem cell exosomes accelerates wound healing via miR-378a/FGF2 axis

Aim: The effects of MALAT1 from human adipose-derived stem cell (ADSC) exosomes in skin wound healing were investigated. Material & methods: The viability, apoptosis and migration ability of human skin fibroblasts (HSFs) were evaluated by Cell Counting Kit-8 assay, flow cytometry and scratch assay, respectively. A mouse model was established to evaluate the role of exosomal MALAT1 in skin wound healing in vivo. Results: Human ADSC exosomes promoted the proliferation and migration of HSFs and increased MALAT1 expression. MALAT1 silencing in human ADSCs inhibited HSF viability and migration, promoted HSF apoptosis and inhibited angiogenesis by upregulating miR-378a. Overexpression of miR-378a inhibited the migration and proliferation of HSFs by downregulating FGF2 expression. ADSC exosomes promoted skin wound healing by mediating MALAT1 in vivo. Conclusion: Exosomal MALAT1 accelerated skin wound healing by regulating the miR-378a/FGF2 axis, suggesting that MALAT1 might be used as a potential target for cutaneous wound treatment.

Highlights on Advancing Frontiers in Tissue Engineering

The field of tissue engineering continues to advance, sometimes in exponential leaps forward, but also sometimes at a rate that does not fulfill the promise that the field imagined a few decades ago. This review is in part a catalog of success in an effort to inform the process of innovation. Tissue engineering has recruited new technologies and developed new methods for engineering tissue constructs that can be used to mitigate or model disease states for study. Key to this antecedent statement is that the scientific effort must be anchored in the needs of a disease state and be working toward a functional product in regenerative medicine. It is this focus on the wildly important ideas coupled with partnered research efforts within both academia and industry that have shown most translational potential. The field continues to thrive and among the most important recent developments are the use of three-dimensional bioprinting, organ-on-a-chip, and induced pluripotent stem cell technologies that warrant special attention. Developments in the aforementioned areas as well as future directions are highlighted in this article. Although several early efforts have not come to fruition, there are good examples of commercial profitability that merit continued investment in tissue engineering. Impact statement Tissue engineering led to the development of new methods for regenerative medicine and disease models. Among the most important recent developments in tissue engineering are the use of three-dimensional bioprinting, organ-on-a-chip, and induced pluripotent stem cell technologies. These technologies and an understanding of them will have impact on the success of tissue engineering and its translation to regenerative medicine. Continued investment in tissue engineering will yield products and therapeutics, with both commercial importance and simultaneous disease mitigation.

Concentrated Growth Factors Promote hBMSCs Osteogenic Differentiation in a Co-Culture System With HUVECs

Osteogenesis is a complex physiologic process that occurs during bone regeneration. This process requires several growth factors that act on bone marrow-derived mesenchymal stem cells (BMSCs). Concentrated growth factor (CGF) is a new-generation platelet-rich derivative that is an appealing autologous material for application in tissue repair and bone regenerative medicine because it contains a variety of fibrin and growth factors. In this study, the effects of CGF on the proliferation and osteogenic differentiation of hBMSCs and human umbilical vein endothelial cells (HUVECs) were explored with in vitro cell co-culture experiments. HBMSCs and HUVECs were directly co-cultured at the ratio of 1:2 under different concentrations (0, 2, 5, 10, 20%) of CGF for 7 days. Alkaline phosphatase (ALP) staining and quantitative reverse transcription polymerase chain reaction were used to detect the effects of CGF on the expression of osteogenic genes (ALP, osteocalcin [OCN], type I collagen [COL-1], Runt-related transcription factor 2 [RUNX2]) and connexin 43 (CX43). RNA sequencing was used to explore potential regulated genes and signaling pathways that affect the osteogenesis of co-cultured hBMSCs exposed to CGF. The results showed higher expressions of ALP, COL-1, RUNX2, OCN, and CX43 in the direct co-culture group containing 10% CGF compared to the direct co-culture group without CGF and the indirect co-culture group. In summary, 10% CGF can significantly promote osteogenesis in hBMSCs directly co-cultured with HUVECs. Intercellular communication between the direct co-culture of hBMSCs and HUVECs through CX43 may be one of the main regulatory mechanisms.

Functional tissue-engineered microtissue formed by self-aggregation of cells for peripheral nerve regeneration

Background

Peripheral nerve injury (PNI) is one of the essential causes of physical disability with a high incidence rate. The traditional tissue engineering strategy, Top-Down strategy, has some limitations. A new tissue-engineered strategy, Bottom-Up strategy (tissue-engineered microtissue strategy), has emerged and made significant research progress in recent years. However, to the best of our knowledge, microtissues are rarely used in neural tissue engineering; thus, we intended to use microtissues to repair PNI.

Methods

We used a low-adhesion cell culture plate to construct adipose-derived mesenchymal stem cells (ASCs) into microtissues in vitro, explored the physicochemical properties and microtissues components, compared the expression of cytokines related to nerve regeneration between microtissues and the same amount of two-dimension (2D)-cultured cells, co-cultured directly microtissues with dorsal root ganglion (DRG) or Schwann cells (SCs) to observe the interaction between them using immunocytochemistry, quantitative reverse transcription polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA). We used grafts constructed by microtissues and polycaprolactone (PCL) nerve conduit to repair sciatic nerve defects in rats.

Results

The present study results indicated that compared with the same number of 2D-cultured cells, microtissue could secrete more nerve regeneration related cytokines to promote SCs proliferation and axons growth. Moreover, in the direct co-culture system of microtissue and DRG or SCs, axons of DRG grown in the direction of microtissue, and there seems to be a cytoplasmic exchange between SCs and ASCs around microtissue. Furthermore, microtissues could repair sciatic nerve defects in rat models more effectively than traditional 2D-cultured ASCs.

Conclusion

Tissue-engineered microtissue is an effective strategy for stem cell culture and therapy in nerve tissue engineering.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02676-0.

Retina stem cells, hopes and obstacles

Retinal degeneration is a major contributor to visual dysfunction worldwide. Although it comprises several eye diseases, loss of retinal pigment epithelial (RPE) and photoreceptor cells are the major contributors to their pathogenesis. Early therapies included diverse treatments, such as provision of anti-vascular endothelial growth factor and many survival and trophic factors that, in some cases, slow down the progression of the degeneration, but do not effectively prevent it. The finding of stem cells (SC) in the eye has led to the proposal of cell replacement strategies for retina degeneration. Therapies using different types of SC, such as retinal progenitor cells (RPCs), embryonic SC, pluripotent SCs (PSCs), induced PSCs (iPSCs), and mesenchymal stromal cells, capable of self-renewal and of differentiating into multiple cell types, have gained ample support. Numerous preclinical studies have assessed transplantation of SC in animal models, with encouraging results. The aim of this work is to revise the different preclinical and clinical approaches, analyzing the SC type used, their efficacy, safety, cell attachment and integration, absence of tumor formation and immunorejection, in order to establish which were the most relevant and successful. In addition, we examine the questions and concerns still open in the field. The data demonstrate the existence of two main approaches, aimed at replacing either RPE cells or photoreceptors. Emerging evidence suggests that RPCs and iPSC are the best candidates, presenting no ethical concerns and a low risk of immunorejection. Clinical trials have already supported the safety and efficacy of SC treatments. Serious concerns are pending, such as the risk of tumor formation, lack of attachment or integration of transplanted cells into host retinas, immunorejection, cell death, and also ethical. However, the amazing progress in the field in the last few years makes it possible to envisage safe and effective treatments to restore vision loss in a near future.

Efficient cell transplantation combining injectable hydrogels with control release of growth factors

Introduction

The objective of this study is to investigate the effect of gelatin microspheres incorporating growth factors on the therapeutic efficacy in cell transplantation. The strength of this study is to combine gelatin hydrogel microspheres incorporating basic fibroblast growth factor and platelet growth factor mixture (GM/GF) with bioabsorbable injectable hydrogels (iGel) for transplantation of adipose-derived stem cells (ASCs).

Methods

The rats ASCs suspended in various solutions were transplanted in masseter muscle. Rats were euthanized 2, 7, 14 days after injection for measurement of the number of ASCs retention in the muscle and morphological evaluation of muscle fibers and the inflammation of the injected tissue by histologic and immunofluorescent stain.

Results

Following the injection into the skeletal muscle, the GM/GF allowed the growth factors to release at the injection site over one week. When ASCs were transplanted into skeletal muscle using iGel incorporating GM/GF (iGel+GM/GF), the number of cells grafted was significantly high compared with other control groups. Moreover, for the groups to which GM/GF was added, the cells transplanted survived, and the Myo-D expression of a myoblast marker was observed at the region of cells transplanted.

Conclusions

The growth factors released for a long time likely enhance the proliferative and differentiative capacity of cells. The simple combination with iGel and GM/GF allowed ASCs to enhance their survival at the injected site and consequently achieve improved therapeutic efficacy in cell transplantation.

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The rats adipose-derived stem cells (ASCs) suspended in various solutions were transplanted in masseter muscle.

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The number of cells transplanted using this study's technology was significantly high compared with other control groups.

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For the groups with growth factors, the Myo-D (myoblast marker) expression was observed at the region of cells transplanted.

Adipogenic Stimulation and Pyrrolidine Dithiocarbamate Induced Osteogenic Inhibition of Dental Pulp Stem Cells Is Countered by Cordycepin

BACKGROUND

dental pulp-derived stem cells are easy to access and collect and are an excellent source of stem cells for regenerative therapy. These cells can interact with many biomolecules and scaffolds and can pass on the instructive signals to the sites of regeneration where they are used. In this regard cordycepin, a potential biomolecule derived from medicinal mushrooms with a spectrum of bioactive properties such as antioxidant, anti-inflammatory, and anticancer has not yet been tested for its effect on human dental pulp stem cells.

OBJECTIVE

the objective of the present study was to assess the in vitro adipogenic and osteogenic differentiation potential of human dental pulp stem cells with or without induction after administration of cordycepin.

MATERIALS AND METHODS

human dental pulp stem cells DPSCs were isolated from a healthy permanent tooth extracted for orthodontic purposes after obtaining informed consent. Flow cytometry technique was used to assess the surface markers of these cells such as CD73, CD90, and CD105, CD34, CD45, and HLA-DR. Further, an MTT assay was performed on the cells after subjecting them to various concentrations of cordycepin. Following this, the adipogenic and osteogenic potential of the dental pulp stem cells was assessed with or without induction under the influence/absence of 5 µM of cordycepin. The results obtained were statistically analyzed and documented.

RESULTS

it was found that the dental pulp stem cells showed strong positive expression for CD73, CD90, and CD105 and faint expression of CD34, CD45, and HLA-DR. MTT assay revealed that 5 µM was the optimum concentration of cordycepin for all the assays. Concerning adipogenesis experiments, there was a statistically significant lowering of all the 4 adipogenesis-related genes PPARγ, FABP4, LPL, and C/EBPα following cordycepin treatment in the presence of induction compared to the only induction group and untreated control cells (p < 0.05). In connection with osteogenesis, was found that there was a statistically significant increase in the expression of RUNX2, COL1A1, OSX and OCN genes along with the increase in alkaline phosphatase and alizarin red staining in the DPSC treated with cordycepin along with the presence of induction and simultaneous addition of PDTC compared to the control untreated cells and cells treated with induction and simultaneous addition of PDTC (p < 0.05).

CONCLUSION

cordycepin can be exploited for its osteopromotive properties and can be used as a bioactive molecule alongside the administration of dental pulp stem cells in the area of regenerative biology and medicine.

Application of mesenchymal stem cells in corneal regeneration

Due to delicate its structure, the cornea is susceptible to physical, chemical, and genetic damages. Corneal transplantation is the main treatment for serious corneal damage, but it faces significant challenges, including donor shortages and severe complications. In recent years, cell therapy is suggested as a novel alternative method for corneal regeneration. Regarding the unique characteristics of Mesenchymal stem cells including the potential to differentiate into discrete cell types, secretion of growth factors, mobilization potency, and availability from different sources; special attention has been paid to these cells in corneal engineering. Differentiation of MSCs into specialized corneal cells such as keratocytes, epithelial and endothelial cells is reported. Potential for Treatment of keratitis, reducing inflammation, and inhibition of neovascularization by MSCs, introducing them as novel agents for corneal repairing. In this review, various types of MSCs used to treat corneal injuries as well as their potential for restoring different corneal layers was investigated.

Effect of Biomedical Materials in the Implementation of a Long and Healthy Life Policy

This paper is divided into seven main parts. Its purpose is to review the literature to demonstrate the importance of developing bioengineering and global production of biomaterials to care for the level of healthcare in the world. First, the general description of health as a universal human value and assumptions of a long and healthy life policy is presented. The ethical aspects of the mission of medical doctors and dentists were emphasized. The coronavirus, COVID-19, pandemic has had a significant impact on health issues, determining the world’s health situation. The scope of the diseases is given, and specific methods of their prevention are discussed. The next part focuses on bioengineering issues, mainly medical engineering and dental engineering, and the need for doctors to use technical solutions supporting medicine and dentistry, taking into account the current stage Industry 4.0 of the industrial revolution. The concept of Dentistry 4.0 was generally presented, and a general Bioengineering 4.0 approach was suggested. The basics of production management and the quality loop of the product life cycle were analyzed. The general classification of medical devices and biomedical materials necessary for their production was presented. The paper contains an analysis of the synthesis and characterization of biomedical materials supporting medicine and dentistry, emphasizing additive manufacturing methods. Numerous examples of clinical applications supported considerations regarding biomedical materials. The economic conditions for implementing various biomedical materials groups were supported by forecasts for developing global markets for biomaterials, regenerative medicine, and tissue engineering. In the seventh part, recapitulation and final remarks against the background of historical retrospection, it was emphasized that the technological processes of production and processing of biomedical materials and the systematic increase in their global production are a determinant of the implementation of a long and healthy policy.

Oxysterols and mesenchymal stem cell biology

Mesenchymal stem cells have the ability to differentiate into several cell types when exposed to determined substances, including oxysterols. Oxysterols are cholesterol products derived from its auto-oxidation by reactive species or from enzymatic action. They are present in the body in low quantities under physiological conditions and exhibit several physiological and pharmacological actions according to both the types of oxysterol and tissue. Some of them are cytotoxic while others have been shown to promote cell differentiation through the action on several different receptors, such as nuclear LXR receptors and Smoothened receptor ligands. Here, we review the main pathways by which oxysterols have been associated with cell differentiation and death of mesenchymal stem cells.

Mesenchymal Stem Cells Derived from Wharton's Jelly Can Differentiate into Schwann Cell-Like Cells and Promote Peripheral Nerve Regeneration in Acellular Nerve Grafts

BACKGROUND

Schwann cells (SCs) secrete neurotrophic factors and provide structural support and guidance during axonal regeneration. However, nearby nerves may be damaged to obtain primary SCs, and there is a lack of nervous tissue donors. We investigated the potential of Wharton's Jelly-derived mesenchymal stem cells (WJ-MSCs) in differentiating into Schwann cell-like cells (WJ-SCLCs) as an alternative to SCs. We also examined whether implantation of WJ-SCLCs-laden acellular nerve grafts (ANGs) are effective in inducing functional recovery and nerve regeneration in an animal model of peripheral nerve injury.

METHODS

The differentiation of WJ-MSCs into WJ-SCLCs was determined by analyzing SC-specific markers. The secretion of neurotrophic factors was assessed by the Neuro Discovery antibody array. Neurite outgrowth and myelination of axons were found in a co-culture system involving motor neuron cell lines. The effects of ANGs on repairing sciatic nerves were evaluated using video gait angle test, isometric tetanic force analysis, and toluidine blue staining.

RESULTS

Compared with undifferentiated WJ-MSCs, WJ-SCLCs showed higher expression levels of SC-specific markers such as S100β, GFAP, KROX20, and NGFR. WJ-SCLCs also showed higher secreted amounts of brain-derived neurotrophic factor, glial cell-derived neurotrophic factor, and granulocyte-colony stimulating factor than did WJ-MSCs. WJ-SCLCs effectively promoted the outgrowth and myelination of neurites in motor neuron cells, and WJ-SCLCs laden ANGs significantly facilitated peripheral nerve regeneration in an animal model of sciatic nerve injury.

CONCLUSION

WJ-MSCs were readily differentiated into WJ-SCLCs, which effectively promoted the regeneration of peripheral nerves. Transplantation of WJ-SCLCs with ANGs might be useful for assisting peripheral nerve regeneration.

Geographical differences in carpometacarpal joint osteoarthritis treatment of the thumb: A survey of 1138 hand surgeons from the USA and Europe

BACKGROUND

Carpometacarpal osteoarthritis of the thumb (CMC OA) is treated with various therapeutic approaches. However, the literature remains inconclusive regarding the ideal procedure for each disease stage. In this study, we assessed the international application of surgical treatment options including CMC I implants and non-surgical treatment options for CMC OA depending on the disease stage, with a strong focus on the detection of geographical disparities.

METHODS

We conducted a large international online survey with members of hand surgical societies of the International Federation of Societies for Surgery of the Hand (IFSSH). The first part of the survey asked about general therapy options of CMC OA depending on the severity of the disease, whereas the second part specifically dealt with the use of prostheses.

RESULTS

We could include 10 of 56 IFSSH member societies (6807 surgeons) and received answers from 1138 members (16.7%). Significant differences were detected in an increased use of corticosteroid injections in the USA, and a growing frequency of fat injections in Europe. Regarding use and frequency of the resection arthroplasty, we found similar results in all participating countries. Prosthetic implantation showed a significant difference between the USA and Europe, with far larger numbers stated by European hand surgeons.

CONCLUSION

CMC OA is treated differently in the participating countries depending on the stage of the disease. We give an insight into geographical differences in treatment paradigms, with corticosteroid injections being more prevalent in the USA, and prosthesis implantation being more frequently chosen in the selected European countries.

Preclinical Applications of Magnetic Resonance Imaging in Oncology

The evolving possibilities of molecular imaging (MI) are fundamentally changing the way we look at cancer, with imaging paradigms now shifting away from basic morphological measures toward the longitudinal assessment of functional, metabolic, cellular, and molecular information in vivo. Recent developments of imaging methodology and probe molecules utilizing the vast number of novel animal models of human cancers have enhanced our ability to non-invasively characterize neoplastic tissue and follow anticancer treatments. While preclinical molecular imaging offers a whole palette of excellent methodology to choose from, we will focus on magnetic resonance imaging (MRI) techniques, since they provide excellent molecular imaging capabilities and bear high potential for clinical translation. Prerequisites and consequences of using animal models as surrogates of human cancers in preclinical molecular imaging are outlined. We present physical principles, values, and limitations of MRI as molecular imaging modality and comment on its high potential to non-invasively assess information on metabolism, hypoxia, angiogenesis, and cell trafficking in preclinical cancer research.

Osteoporotic Conditions Influence the Activity of Adipose-Derived Stem Cells

BACKGROUND

Estrogen deficiency decreases bone density and increases the risk of osteoporosis and fracture, thereby necessitating reconstruction of bone regeneration. As bone marrow mesenchymal stem cell (BMSCs) lose viability and differentiation potential under osteoporotic conditions, it is impossible to use autologous BMSCs for osteoporosis treatment. As an alternative, adipose-derived stem cells (ADSCs) may serve as the source of therapeutic cells.

METHOD

We evaluated the effects of osteoporosis on the functional characteristics of ADSCs. Osteoporosis was induced in ovariectomy (OVX) rat model, and the ADSCs from Sham and OVX groups were cultured and analyzed comparatively.

RESULTS

As a result, the viability was higher for the ADSCs from Sham group than those from OVX group. The analysis of the paracrine potential of ADSCs revealed the elevated levels of inflammatory and cellular senescence factors in the ADSCs from OVX group. The ADSCs from OVX group had much higher differentiation potential into adipocytes than those from the Sham group. Osteoporotic environment had no effect on the osteogenic potential of ADSCs.

CONCLUSION

Osteoporosis may reduce the activity and influence immune response of ADSCs by modulating paracrine action and adipogenic potential. These characteristics of ADSCs should be given consideration for therapeutic purpose.

Three-dimensional culture of dental pulp pluripotent-like stem cells (DPPSCs) enhances Nanog expression and provides a serum-free condition for exosome isolation

Stem cell-derived exosomes have been identified as novel cell-free therapeutics for regenerative medicine. Three-dimensional (3D) culture of stem cells were reported to improve their "stemness" and therapeutic efficacy. This work focused on establishing serum-free 3D culture of dental pulp pluripotent-like stem cells (DPPSCs)-a newly characterized pluripotent-like stem cell for exosome production. DPPSCs were expanded in regular 2D culture in human serum-supplemented (HS)-medium and transferred to a micropatterned culture plate for 3D culture in HS-medium (default) and medium supplemented with KnockOut™ serum replacement (KO-medium). Bright-field microscopy observation throughout the culture period (24 days) revealed that DPPSCs in KO-medium formed spheroids of similar morphology and size to that in HS-medium. qRT-PCR analysis showed similar Oct4A gene expression in DPPSC spheroids in both HS-medium and KO-medium, but Nanog expression significantly increased in the latter. Vesicles isolated from DPPSC spheroids in KO-medium in the first 12 days of culture showed sizes that fall within the exosomal size range by nanoparticle tracking analysis (NTA) and express the canonical exosomal markers. It is concluded that 3D culture of DPPSCs in KO-medium provided an optimal serum-free condition for successful isolation of DPPSC-derived exosomes for subsequent applications in regenerative medicine.

A Patch of Detachable Hybrid Microneedle Depot for Localized Delivery of Mesenchymal Stem Cells in Regeneration Therapy

Mesenchymal stem cells (MSCs) have been widely used for regenerative therapy. In most current clinical applications, MSCs are delivered by injection but face significant issues with cell viability and penetration into the target tissue due to a limited migration capacity. Some therapies have attempted to improve MSC stability by their encapsulation within biomaterials; however, these treatments still require an enormous number of cells to achieve therapeutic efficacy due to low efficiency. Additionally, while local injection allows for targeted delivery, injections with conventional syringes are highly invasive. Due to the challenges associated with stem cell delivery, a local and minimally invasive approach with high efficiency and improved cell viability is highly desired. In this study, we present a detachable hybrid microneedle depot (d-HMND) for cell delivery. Our system consists of an array of microneedles with an outer poly(lactic-co-glycolic) acid (PLGA) shell and an internal gelatin methacryloyl (GelMA)-MSC mixture (GMM). The GMM was characterized and optimized for cell viability and mechanical strength of the d-HMND required to penetrate mouse skin tissue was also determined. MSC viability and function within the d-HMND was characterized in vitro and the regenerative efficacy of the d-HMND was demonstrated in vivo using a mouse skin wound model.

Cardiac tissue remodeling in healthy aging: the road to pathology

This review aims to highlight the normal physiological remodeling that occurs in healthy aging hearts, including changes that occur in contractility, conduction, valve function, large and small coronary vessels, and the extracellular matrix. These "normal" age-related changes serve as the foundation that supports decreased plasticity and limited ability for tissue remodeling during pathophysiological states such as myocardial ischemia and heart failure. This review will identify populations at greater risk for poor tissue remodeling in advanced age along with present and future therapeutic strategies that may ameliorate dysfunctional tissue remodeling in aging hearts.

Stammzellen in der Regenerativen Medizin – Translationale Hürden und Möglichkeiten zur Überwindung

Der Einsatz von mesenchymalen Stammzellen in der regenerativen Medizin wird immer populärer. Nichtsdestotrotz ist ihre Anwendung im klinischen Alltag noch immer limitiert. Zahlreiche ethische, rechtliche und translationale Probleme sowie Ungewissheit bzgl. der Sicherheit hemmen noch immer die Entstehung von entsprechenden Therapien aus vielversprechenden wissenschaftlichen Ansätzen.

Diese Arbeit soll die Hauptprobleme bei der Translation von stammzellbasierten Therapien aus der Grundlagenforschung und Präklinik in den klinischen Alltag darstellen, sowie Ansätze aufzeigen, diese zu überwinden.

Inhibition of DNA Methyltransferase by RG108 Promotes Pluripotency-Related Character of Porcine Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem/stromal cells (MSCs) have been identified in almost all adult human tissues and been used in numerous clinical trials for a variety of diseases. Studies have shown that MSCs would undergo cellular senescence when cultured over a long term, which is brought on by increased epigenetic modifications, including DNA methylation. However, the mechanism of MSCs senescence is not well studied. In this study, the effects of RG108, a DNA methyltransferase inhibitor (DNMTi), on senescence, apoptosis, and pluripotency gene expressions in porcine bone marrow (pBM)-MSCs were investigated. First, we determined the optimized dose and time of RG108 treatment in pBM-MSCs to be 10 μM for 48 hours, respectively. Under these conditions, the pluripotency genes (NANOG, POU5F1), the anti-senescence genes (TERT, bFGF), and the anti-apoptosis gene (BCL2) were increased, whereas the apoptotic gene (BAX) was decreased. RG108 protected against apoptosis when pBM-MSC induces apoptosis with H₂O₂ for 1.5 hours. We also found that RG108 significantly induced the expression of NANOG and POU5F1 by decreasing DNA methylation in gene promoter regions. These results indicate that an optimized dose of RG108 may promote the pluripotency-related character of pBM-MSCs through improving cellular anti-senescence, anti-apoptosis, and pluripotency, which provide a better cell origin for stem cell therapy.

Stem Cell Aging and Regenerative Medicine

Stem cells are a promising source for regenerative medicine to cure a plethora of diseases that are currently treated based on either palliative or symptomatic relief or by preventing their onset and progression. Aging-associated degenerative changes in stem cells, stem cell niches, and signaling pathways bring a step by step decline in the regenerative and functional potential of tissues. Clinical studies and experiments on model organisms have pointed out checkpoints that aging will inevitably impose on stem cell aiming for transplantation and hence questions are raised about the age of the donor. In the following discourse, we review the fundamental molecular pathways that are implicated in stem cell aging and the current progress in tissue engineering and transplantation of each type of stem cells in regenerative medicine. We further focus on the consequences of stem cell aging on their clinical uses and the development of novel strategies to bypass those pitfalls and improve tissue replenishment.

Design of injectable hydrogels of gelatin and alginate with ferric ions for cell transplantation

The objective of this study is to design bioabsorbable injectable hydrogels based on the physico-chemical interaction between biocompatible polymers and ferric ions, and evaluate the survival, proliferation, and osteogenic differentiation of cells encapsulated in the hydrogels. The injectable hydrogels were prepared by simply mixing mixed alginate/gelatin solution at various ratios and FeCl₃ solution. The hydrogels prepared disappeared within a few days in the phosphate buffered-saline solution (PBS) with containing collagenase although the disappearance rate increased with an increase of the gelatin ratio in the hydrogel. For the hydrogel of alginate/gelatin low ratio, the survival and proliferation of cells in the hydrogel-encapsulated condition were significantly high compared with those of hydrogel at the higher ratios. The cells collected 3 days after cultured in the hydrogel also proliferated to a significantly higher extent than those collected from other hydrogels. The proliferation ability of cells was similar that of cells cultured on the standard tissue culture polystyrene (TCPS) dish. When evaluated to compare with cells cultured on the TCPS dish, the expression of runt-related transcription factor-2 (RUNX2) gene, the alkaline phosphatase (ALP) activity, and the calcium precipitation were significantly high. The cells were encapsulated by the mixed alginate/gelatin and FeCl₃ hydrogel and injected in the back subcutis of mice, the percentage of cells retained in the injected site was higher than that of cells injected in the PBS suspension. It is concluded that the injectable hydrogel prepared by simple mixing mixed alginate/gelatin solution and FeCl₃ solution is a promising material for the cell transplantation. STATEMENT OF SIGNIFICANCE: Injectable hydrogels prepared by simple mixing mixed alginate/gelatin solution at various ratios and FeCl₃ solution. For the hydrogel of alginate/gelatin low ratio, the survival, the proliferation, and the differentiate properties of cells in the hydrogel-encapsulated condition were similar those of cells cultured on the TCPS dish. When the cells encapsulated hydrogels were injected in the back subcutis of mice, the percentage of cells retained in the injected site was higher than that of cells injected in the PBS suspension. It is concluded that the present injectable hydrogel is a promising material for the cell transplantation.

Effective stacking and transplantation of stem cell sheets using exogenous ROS-producing film for accelerated wound healing

Extensive skin loss caused by burns or diabetic ulcers may lead to major disability or even death. Therefore, cell-based therapies that enhance skin regeneration are clinically needed. Previous approaches have been applied the injections of cell suspensions and the implantation of biodegradable three-dimensional scaffolds seeded cells. However, these treatments have limits due to poor localization of the injected cells and insufficient delivery of oxygen and nutrients to cells. Recently, cell sheet-based tissue engineering has been developed to transplant cell sheets, which are cell-dense tissues without scaffolds. Because cell density is one of the important factors for improving the therapeutic effect of cell transplantation, transplanting layered cell sheet constructs can promote the recovery of tissue function and tissue regeneration compared with a single cell sheet. Thus, this study designed ROS-induced cell sheet stacking method with newly fabricated hematoporphyrin-incorporated polyketone film (Hp-PK film) to enhance cell sheet delivery efficiency and application in wound healing. We have demonstrated the therapeutic effect of a multi-layered mesenchymal stem cell sheets onto a full-thickness wound defect in nude mice. Consequentially, three-layered cell sheets transplanted and stacked by ROS-induced method promoted angiogenesis and skin regeneration at the wound site. Thus, our strategy based on Hp-PK film, which allows for easy stacking and transplantation of cell sheets, could be applied to enhance tissue regeneration. STATEMENT OF SIGNIFICANCE: We herein report exogenous ROS-induced cell sheet stacking method with newly fabricated hematoporphyrin-incorporated polyketone film (Hp-PK film) to enhance cell sheet transplantation efficiency and application in wound healing. Although there are several ways to stack-up cell sheets, all of these methods have limitations in transplanting the cell sheet directly to the target site. The method is simple and takes a relatively short time compared to previously reported methods for stacking and transplanting cell sheets. Thus, our study will provide a scientific impact because the method of applying exogenous ROS generated from Hp-PK film on cell detachment can transplant the cell sheet through a process of putting a cell sheet-cultured film on the lesion, irradiating with light, and then removing only the film.

Advancing Frontiers in Bone Bioprinting

Three-dimensional (3D) bioprinting of cell-laden biomaterials is used to fabricate constructs that can mimic the structure of native tissues. The main techniques used for 3D bioprinting include microextrusion, inkjet, and laser-assisted bioprinting. Bioinks used for bone bioprinting include hydrogels loaded with bioactive ceramics, cells, and growth factors. In this review, a critical overview of the recent literature on various types of bioinks used for bone bioprinting is presented. Major challenges, such as the vascularity, clinically relevant size, and mechanical properties of 3D printed structures, that need to be addressed to successfully use the technology in clinical settings, are discussed. Emerging approaches to solve these problems are reviewed, and future strategies to design customized 3D printed structures are proposed.

Immunohematology Mesenchymal Stromal Cell-based Therapy: From Research to Clinic

Mesenchymal stromal cells (MSC) are nonhematopoietic cells that can be isolated from several adult and fetal tissues. MSC present specific features as the capacity to support hematopoiesis and to regulate immune response. Thus, the use of MSC as a cell therapeutic product in the field of immune-hematology is of great importance. In this review, we focused on human MSC and discussed their immune-hematologic properties and their translation toward therapeutic clinical applications. Thus, these features hold great promise for cell-based therapy and are of important relevance for the field.

Three Dimensional Printed Bone Implants in the Clinic

Implants are being continuously developed to achieve personalized therapy. With the advent of 3-dimensional (3D) printing, it is becoming possible to produce customized precisely fitting implants that can be derived from 3D images fed into 3D printers. In addition, it is possible to combine various materials, such as ceramics, to render these constructs osteoconductive or growth factors to make them osteoinductive. Constructs can be seeded with cells to engineer bone tissue. Alternatively, it is possible to load cells into the biomaterial to form so called bioink and print them together to from 3D bioprinted constructs that are characterized by having more homogenous cell distribution in their matrix. To date, 3D printing was applied in the clinic mostly for surgical training and for planning of surgery, with limited use in producing 3D implants for clinical application. Few examples exist so far, which include mostly the 3D printed implants applied in maxillofacial surgery and in orthopedic surgery, which are discussed in this report. Wider clinical application of 3D printing will help the adoption of 3D printers as essential tools in the clinics in future and thus, contribute to realization of personalized medicine.

Fibrin Glue Enhances Adipose-Derived Stromal Cell Cytokine Secretion and Survival Conferring Accelerated Diabetic Wound Healing

Introduction

Although chronic wounds are a major personal and economic burden, treatment options are still limited. Among those options, adipose-derived stromal cell- (ASC-) based therapies rank as a promising approach but are restricted by the harsh wound environment. Here we use a commercially available fibrin glue to provide a deliverable niche for ASCs in chronic wounds.

Material and Methods

To investigate the in vitro effect of fibrin glue, cultivation experiments were performed and key cytokines for regeneration were quantified. By using an established murine chronic diabetic wound-healing model, we evaluated the influence of fibrin glue spray seeding on cell survival (In Vivo Imaging System, IVIS), wound healing (wound closure kinetics), and neovascularization of healed wounds (CD31 immunohistochemistry).

Results

Fibrin glue seeding leads to a significantly enhanced secretion of key cytokines (SDF-1, bFGF, and MMP-2) of human ASCs in vitro. IVIS imaging showed a significantly prolonged murine ASC survival in diabetic wounds and significantly accelerated complete wound closure in the fibrin glue seeded group. CD31 immunohistochemistry revealed significantly more neovascularization in healed wounds treated with ASCs spray seeded in fibrin glue vs. ASC injected into the wound bed.

Conclusion

Although several vehicles have shown to successfully act as cell carrier systems in preclinical trials, regulatory issues have prohibited clinical usage for chronic wounds. By demonstrating the ability of fibrin glue to act as a carrier vehicle for ASCs, while simultaneously enhancing cellular regenerative function and viability, this study is a proponent of clinical translation for ASC-based therapies.

Isolation and multipotential differentiation of mesenchymal stromal cell‑like progenitor cells from human bladder

Various types of mesenchymal stromal cells (MSCs) have been used in urological tissue engineering but to date the existence of MSCs has not been reported in the human bladder. The present study provided evidence that a small number of MSC‑like cells exist in the human bladder and designated this class of cells 'human bladder‑derived MSC‑like cells' (hBSCs). It was demonstrated that hBSCs can be cultured to yield a large population. These hBSCs expressed the surface markers of MSCs and exhibited the capacity for osteogenic, adipogenic and chondrogenic differentiation. On induction with appropriate media in vitro, hBSCs could differentiate into bladder‑associated cell types, including urothelial, endothelial and smooth muscle cell‑like lineages. In addition, the average telomerase activity of adult hBSCs was higher compared with adult human bone marrow‑derived MSCs, but lower than that of human umbilical cord Wharton's jelly‑derived MSCs. These findings may inspire future studies on the role of hBSCs in urological tissue engineering applications and in other fields.

Intra-Articular Administration of Autologous Micro-Fragmented Adipose Tissue in Dogs with Spontaneous Osteoarthritis: Safety, Feasibility, and Clinical Outcomes

Similar to the disease affecting humans, osteoarthritis (OA) is a painful musculoskeletal condition affecting 20% of the adult canine population. Several solutions have been proposed, but the results achieved to date are far from being satisfactory. New approaches, such as intra-articular delivery of cells (including mesenchymal stromal cells), have been proposed. Among the many sources, the adipose tissue is considered very promising. We evaluated the safety, feasibility, and efficacy of a single intra-articular injection of autologous and micro-fragmented adipose tissue (MFAT) in 130 dogs with spontaneous OA. MFAT was obtained using a minimally invasive technique in a closed system and injected in the intra- and/or peri-articular space. Clinical outcomes were determined using orthopedic examination and owners' scores for up to 6 months. In 78% of the dogs, improvement in the orthopedic score was registered 1 month after treatment and continued gradually up to 6 months when 88% of the dogs improved, 11% did not change, and 1% worsened compared with baseline. Considering the owners' scores at 6 months, 92% of the dogs significantly improved, 6% improved only slightly, and 2% worsened compared with baseline. No local or systemic major adverse effects were recorded. The results of this study suggest that MFAT injection in dogs with OA is safe, feasible, and beneficial. The procedure is time sparing and cost-effective. Post injection cytological investigation, together with the clinical evidence, suggests a long-term pain control role of this treatment. The spontaneous OA dog model has a key role in developing successful treatments for translational medicine. Stem Cells Translational Medicine 2018;7:819-828.

Preparation of cationized gelatin nanospheres incorporating molecular beacon to visualize cell apoptosis

The objective of this study is to prepare cationized gelatin nanospheres (cGNS) incorporating a molecular beacon (MB), and visualize cellular apoptosis. Two types of MB to detect the messenger RNA (mRNA) of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (GAP MB), and caspase-3 (casp3 MB) were incorporated in cGNS, respectively. MB incorporated in cGNS showed the DNA sequence specificity in hybridization. The cGNS incorporation enabled MB to enhance the stability against nuclease to a significantly great extent compared with free MB. The cGNS incorporating GAP MB were internalized into the KUM6 of a mouse bone marrow-derived stem cell by an endocytotic pathway. The cGNS were not distributed at the lysosomes. After the incubation with cGNS, the cell apoptosis was induced at different concentrations of camptothecin. No change in the intracellular fluorescence was observed for cGNS_GAPMB. On the other hand, for the cGNS_casp3MB, the fluorescent intensity significantly enhanced by the apoptosis induction of cells. It is concluded that cGNS incorporating MB is a promising system for the visualization of cellular apoptosis.

Targeted Elimination of Tumorigenic Human Pluripotent Stem Cells Using Suicide-Inducing Virus-like Particles

Sensitization to prodrugs via transgenic expression of suicide genes is a leading strategy for the selective elimination of potentially tumorigenic human pluripotent stem cells (hPSCs) in regenerative medicine, but transgenic modification poses safety risks such as deleterious mutagenesis. We describe here an alternative method of delivering suicide-inducing molecules explicitly to hPSCs using virus-like particles (VLPs) and demonstrate its use in eliminating undifferentiated hPSCs in vitro. VLPs were engineered from Qβ bacteriophage capsids to contain enhanced green fluorescent protein (EGFP) or cytosine deaminase (CD) and to simultaneously display multiple IgG-binding ZZ domains. After labeling with antibodies against the hPSC-specific surface glycan SSEA-5, EGFP-containing particles were shown to specifically bind undifferentiated cells in culture, and CD-containing particles were able to eliminate undifferentiated hPSCs with virtually no cytotoxicity to differentiated cells upon treatment with the prodrug 5-fluorocytosine.

<i>In Vitro</i> Comparative Study of Osteogenic Differentiation Ability between Adipose and Bone Marrow Mesenchymal Stem Cell Applied to Bovine Demineralized Bone Matrix

Ideal bone graft must possess the desirable trait such as osteoconductive, osteoinductive and osteogenesis. Demineralized Bone Matrix (DBM) provides both osteoconductive and osteoinductive trait. Referring to the tissue engineering principle, the addition of mesenchymal stem cell would add the osteogenic trait to this procedure. The design of this study is experimental using Bovine DBM. Bone Marrow Mesenchymal Stem Cell (BMSCs) and Adipose Mesenchymal Stem Cells (ASCs) were taken from New Zealand white rabbit. There are two groups of treatment, divided into DBM implanted with BMSCs and DBM implanted with ASCs. Each BMSCs and ASCs groups is incubated in the normal and osteogenic culture plate. Evaluation is performed by counting the osteoblast and immunohistochemistry stain using Alkaline Phosphate and Osteocalcin. After 4 weeks of incubation, we found that the osteoblast count in BMSCs groups is higher compared to the ASCs groups in both culture condition (p<0.01) along with Alkaline Phosphate staining (p<0.05), while the Osteocalcin staining showed insignificant differences (p>0.05). This study revealed that xenogenic bovine DBM can act as the potential osteoinductive scaffold for the MSCs to differentiate. The tissue engineering application by combining MSCs and Bovine DBM can be considered as an alternative in managing bone defect cases.

Comparison of Intraoral Bone Regeneration with Iliac and Alveolar BMSCs

This study compared the osteogenic potential of bone marrow mesenchymal stem cells (BMSCs) of iliac and alveolar origins (I-BMSCs and Al-BMSCs, respectively), which were transplanted in combination with β tricalcium phosphate (β-TCP) in peri-implant bone defects to investigate the osseointegration between dental implants and tissue-engineered bone in dogs. Specifically, I-BMSCs and Al-BMSCs were cultured, characterized, and seeded on β-TCP and subjected to immunoblotting analyses and alkaline phosphatase activity assays. Subsequently, these cell-seeded scaffolds were implanted into defects that were freshly generated in the mandibular premolar areas of 4 dogs. The defects were covered with β-TCP + Al-BMSCs ( n = 6), β-TCP + I-BMSCs ( n = 6), or β-TCP ( n = 6) or served as the blank control ( n = 6). After healing for 12 wk, the formation and mineralization of new bones were assessed through micro-computed tomographic, histologic, and histomorphometric analyses, and bone-to-implant contacts were measured in the specimens. It was evident that in this large animal model, I-BMSCs and Al-BMSCs manifested similarly strong osteogenic potential, as significantly more new bone was formed in the Al-BMSC and I-BMSC groups than otherwise ( P < 0.01). Therefore, Al-BMSCs are emerging as an efficient alternative for autologous mesenchymal stem cells in regenerative dental and maxillofacial therapies. I-BMSCs, if not restricted in their bioavailability, can also be of great utility in bone tissue-engineering applications.