Autologous transplantation of adipose-derived stem cells improves functional recovery of skeletal muscle without direct participation in new myofiber formation

Adipose Decellularized Matrix: A Promising Skeletal Muscle Tissue Engineering Material for Volume Muscle Loss

Volume muscle loss is a severe injury often caused by trauma, fracture, tumor resection, or degenerative disease, leading to long-term dysfunction or disability. The current gold-standard treatment is autologous muscle tissue transplantation, with limitations due to donor site restrictions, complications, and low regeneration efficiency. Tissue engineering shows potential to overcome these challenges and achieve optimal muscle regeneration, vascularization, nerve repair, and immunomodulation. In the field of muscle tissue engineering, skeletal muscle decellularized matrices are regarded as an ideal material due to their similarity to the defect site environment, yet they suffer from difficulties in preparation, severe fibrosis, and inconsistent experimental findings. Adipose decellularized matrices (AdECMs) have demonstrated consistent efficacy in promoting muscle regeneration, and their ease of preparation and abundant availability make them even more attractive. The full potential of AdECMs for muscle regeneration remains to be explored. The aim of this review is to summarize the relevant studies on using AdECMs to promote muscle regeneration, to summarize the preparation methods of various applied forms, and to analyze their advantages and shortcomings, as well as to further explore their mechanisms and to propose possible improvements, so as to provide new ideas for the clinical solution of the problem of volume muscle loss.

Urine-derived stem cells genetically modified with IGF1 improve muscle regeneration

OBJECTIVE

In this study we aimed to determine the impact of human urine derived stem cells (USC) and genetically modified USC that were designed to overexpress myogenic growth factor IGF1 (USCIGF), on the regenerative capacity of cardiotoxin (CTX)-injured murine skeletal muscle.

METHODS

We overexpressed IGF1 in USC and investigated the alterations in myogenic capacity and regenerative function in cardiotoxin-injured muscle tissues.

RESULTS

Compared with USC alone, USCIGF1 activated the IGF1-Akt-mTOR signaling pathway, significantly improved myogenic differentiation capacity in vitro, and enhanced the secretion of myogenic growth factors and cytokines. In addition, IGF1 overexpression increased the ability of USC to fuse with skeletal myocytes to form myotubes, regulated the pro-regenerative immune response and inflammatory cytokines, and increased myogenesis in an in vivo model of skeletal muscle injury.

CONCLUSION

Overall, USC genetically modified to overexpress IGF1 significantly enhanced skeletal muscle regeneration by regulating myogenic differentiation, paracrine effects, and cell fusion, as well as by modulating immune responses in injured skeletal muscles in vivo. This study provides a novel perspective for evaluating the myogenic function of USC as a nonmyogenic cell source in skeletal myogenesis. The combination of USC and IGF1 expression has the potential to provide a novel efficient therapy for skeletal muscle injury and associated muscular defects in patients with urinary incontinence.

Uncovering the link between diabetes and cardiovascular diseases: insights from adipose-derived stem cells

Cardiovascular diseases (CVDs) are the leading causes of morbidity and mortality worldwide. The escalating global occurrence of obesity and diabetes mellitus (DM) has led to a significant upsurge in individuals afflicted with CVDs. As the prevalence of CVDs continues to rise, it is becoming increasingly important to identify the underlying cellular and molecular mechanisms that contribute to their development and progression, which will help discover novel therapeutic avenues. Adipose tissue (AT) is a connective tissue that plays a crucial role in maintaining lipid and glucose homeostasis. However, when AT is exposed to diseased conditions, such as DM, this tissue will alter its phenotype to become dysfunctional. AT is now recognized as a critical contributor to CVDs, especially in patients with DM. AT is comprised of a heterogeneous cellular population, which includes adipose-derived stem cells (ADSCs). ADSCs resident in AT are believed to regulate physiological cardiac function and have potential cardioprotective roles. However, recent studies have also shown that ADSCs from various adipose tissue depots become pro-apoptotic, pro-inflammatory, less angiogenic, and lose their ability to differentiate into various cell lineages upon exposure to diabetic conditions. This review aims to summarize the current understanding of the physiological roles of ADSCs, the impact of DM on ADSC phenotypic changes, and how these alterations may contribute to the pathogenesis of CVDs.

Investigation of Expanded Human Adipose-derived Stem Cell Dosage and Timing for Improved Defecation Function

BACKGROUND/AIM

Although certain treatment options exist for intestinal incontinence, none are curative. Adipose-derived stem cells (ADSCs) have emerged as promising therapeutic agents, but most preclinical studies of their effectiveness for anal function have used autologous or allogeneic ADSCs. In this study, the effectiveness, timing of administration, and required dosage of human ADSCs were investigated for clinical application.

MATERIALS AND METHODS

A 10-mm balloon catheter was used to induce anal sphincter injury in immunodeficient mice in the following experimental groups (n=4 per group): ADSC (injected ADSCs after injury), PBS (injected phosphate-buffered saline after injury), and control (uninjured). The effects of different timing (immediately after injection and 30 days following injury) and number of human ADSCs administered was compared among groups based on defecation status and pathological evaluation.

RESULTS

In terms of defecation status, groups receiving ≥1×104 human ADSCs after injection showed improvement. Pathological images showed that compared to the PBS group, the thinnest part of the sphincter was thicker for animals that received ≥1×104 human ADSCs, and fibrosis of the sphincter was notable in those treated with 1×103 human ADSCs or PBS. Furthermore, defecation status was improved by administration of human ADSCs, not only immediately after injury, but also at 30 days following injury.

CONCLUSION

Human ADSC administration in a mouse model of anal sphincter injury was effective. Injection of ≥1×104 human ADSCs was the amount necessary to improve defecation status, an effect detected in both the acute and chronic phases.

The comparison of adipose-derived stromal cells (ADSCs) delivery method in a murine model of hindlimb ischemia

BACKGROUND

Adipose-derived stromal cells (ADSCs) demonstrate ability to promote tissue healing and down-regulate excessive inflammation. ADSCs have been used to treat critical limb ischemia in preclinical and clinical trials, but still, there is little known about their optimal delivery strategy. To date, no direct analysis of different methods of ADSCs delivery has been performed in the hindlimb ischemia model. Therefore, in this study we focused on the therapeutic efficacy of different ADSCs delivery methods in a murine model of hindlimb ischemia.

METHODS

For the hADSCs isolation, we used the subcutaneous adipose tissue collected during the surgery. The murine hindlimb ischemia was used as a model. The unilateral femoral artery ligation was performed on 10-12-week-old male C57BL/6. ADSCs were delivered directly into ischemic muscle, into the contralateral muscle or intravenously. 7 and 14 days after the surgery, the gastrocnemius and quadriceps muscles were collected for the immunohistochemical analysis. The results were analyzed with relevant tests using the Statistica software.

RESULTS

Our research revealed that muscle regeneration, angiogenesis, arteriogenesis and macrophage infiltration in murine model of hindlimb ischemia differ depending on ADSCs delivery method. We have demonstrated that intramuscular method (directly into ischemic limb) of ADSCs delivery is more efficient in functional recovery after critical limb ischemia than intravenous or contralateral route.

CONCLUSIONS

We have noticed that injection of ADSCs directly into ischemic limb is the optimal delivery strategy because it increases: (1) muscle fiber regeneration, (2) the number of capillaries and (3) the influx of macrophages F4/80+/CD206+.

Nano-biomaterials and advanced fabrication techniques for engineering skeletal muscle tissue constructs in regenerative medicine

Engineered three-dimensional (3D) tissue constructs have emerged as a promising solution for regenerating damaged muscle tissue resulting from traumatic or surgical events. 3D architecture and function of the muscle tissue constructs can be customized by selecting types of biomaterials and cells that can be engineered with desired shapes and sizes through various nano- and micro-fabrication techniques. Despite significant progress in this field, further research is needed to improve, in terms of biomaterials properties and fabrication techniques, the resemblance of function and complex architecture of engineered constructs to native muscle tissues, potentially enhancing muscle tissue regeneration and restoring muscle function. In this review, we discuss the latest trends in using nano-biomaterials and advanced nano-/micro-fabrication techniques for creating 3D muscle tissue constructs and their regeneration ability. Current challenges and potential solutions are highlighted, and we discuss the implications and opportunities of a future perspective in the field, including the possibility for creating personalized and biomanufacturable platforms.

Mesenchymal Stem Cells in Soft Tissue Regenerative Medicine: A Comprehensive Review

Soft tissue regeneration holds significant promise for addressing various clinical challenges, ranging from craniofacial and oral tissue defects to blood vessels, muscle, and fibrous tissue regeneration. Mesenchymal stem cells (MSCs) have emerged as a promising tool in regenerative medicine due to their unique characteristics and potential to differentiate into multiple cell lineages. This comprehensive review explores the role of MSCs in different aspects of soft tissue regeneration, including their application in craniofacial and oral soft tissue regeneration, nerve regeneration, blood vessel regeneration, muscle regeneration, and fibrous tissue regeneration. By examining the latest research findings and clinical advancements, this article aims to provide insights into the current state of MSC-based therapies in soft tissue regenerative medicine.

Mesenchymal stem cells alleviate dexamethasone-induced muscle atrophy in mice and the involvement of ERK1/2 signalling pathway

BACKGROUND

High dosage of dexamethasone (Dex) is an effective treatment for multiple diseases; however, it is often associated with severe side effects including muscle atrophy, resulting in higher risk of falls and poorer life quality of patients. Cell therapy with mesenchymal stem cells (MSCs) holds promise for regenerative medicine. In this study, we aimed to investigate the therapeutic efficacy of systemic administration of adipose-derived mesenchymal stem cells (ADSCs) in mitigating the loss of muscle mass and strength in mouse model of DEX-induced muscle atrophy.

METHODS

3-month-old female C57BL/6 mice were treated with Dex (20 mg/kg body weight, i.p.) for 10 days to induce muscle atrophy, then subjected to intravenous injection of a single dose of ADSCs ([Formula: see text] cells/kg body weight) or vehicle control. The mice were killed 7 days after ADSCs treatment. Body compositions were measured by animal DXA, gastrocnemius muscle was isolated for ex vivo muscle functional test, histological assessment and Western blot, while tibialis anterior muscles were isolated for RNA-sequencing and qPCR. For in vitro study, C2C12 myoblast cells were cultured under myogenic differentiation medium for 5 days following 100 [Formula: see text]M Dex treatment with or without ADSC-conditioned medium for another 4 days. Samples were collected for qPCR analysis and Western blot analysis. Myotube morphology was measured by myosin heavy chain immunofluorescence staining.

RESULTS

ADSC treatment significantly increased body lean mass (10-20%), muscle wet weight (15-30%) and cross-sectional area (CSA) (~ 33%) in DEX-induced muscle atrophy mice model and down-regulated muscle atrophy-associated genes expression (45-65%). Hindlimb grip strength (~ 37%) and forelimb ex vivo muscle contraction property were significantly improved (~ 57%) in the treatment group. Significant increase in type I fibres (~ 77%) was found after ADSC injection. RNA-sequencing results suggested that ERK1/2 signalling pathway might be playing important role underlying the beneficial effect of ADSC treatment, which was confirmed by ERK1/2 inhibitor both in vitro and in vivo.

CONCLUSIONS

ADSCs restore the pathogenesis of Dex-induced muscle atrophy with an increased number of type I fibres, stronger muscle strength, faster recovery rate and more anti-fatigue ability via ERK1/2 signalling pathway. The inhibition of muscle atrophy-associated genes by ADSCs offered this treatment as an intervention option for muscle-associated diseases. Taken together, our findings suggested that adipose-derived mesenchymal stem cell therapy could be a new treatment option for patient with Dex-induced muscle atrophy.

An Update on Adipose-Derived Stem Cells for Regenerative Medicine: Where Challenge Meets Opportunity

Over the last decade, adipose-derived stem cells (ADSCs) have attracted increasing attention in the field of regenerative medicine. ADSCs appear to be the most advantageous cell type for regenerative therapies owing to their easy accessibility, multipotency, and active paracrine activity. This review highlights current challenges in translating ADSC-based therapies into clinical settings and discusses novel strategies to overcome the limitations of ADSCs. To further establish ADSC-based therapies as an emerging platform for regenerative medicine, this review also provides an update on the advancements in this field, including fat grafting, wound healing, bone regeneration, skeletal muscle repair, tendon reconstruction, cartilage regeneration, cardiac repair, and nerve regeneration. ADSC-based therapies are expected to be more tissue-specific and increasingly important in regenerative medicine.

A cross-talk between sestrins, chronic inflammation and cellular senescence governs the development of age-associated sarcopenia and obesity

The rapid increase in both the lifespan and proportion of older adults is accompanied by the unprecedented rise in age-associated chronic diseases, including sarcopenia and obesity. Aging is also manifested by increased susceptibility to multiple endogenous and exogenous stresses enabling such chronic conditions to develop. Among the main physiological regulators of cellular adaption to various stress stimuli, such as DNA damage, hypoxia, and oxidative stress, are sestrins (Sesns), a family of three evolutionarily conserved proteins, Sesn1, 2, and 3. Age-associated sarcopenia and obesity are characterized by two key processes: (i) accumulation of senescent cells in the skeletal muscle and adipose tissue and (ii) creation of a systemic, chronic, low-grade inflammation (SCLGI). Presumably, failed SCLGI resolution governs the development of these chronic conditions. Noteworthy, Sesns activate senolytics, which are agents that selectively eliminate senescent cells, as well as specialized pro-resolving mediators, which are factors that physiologically provide inflammation resolution. Sesns reveal clear beneficial effects in pre-clinical models of sarcopenia and obesity. Based on these observations, we propose a novel treatment strategy for age-associated sarcopenia and obesity, complementary to the conventional therapeutic modalities: Sesn activation, SCLGI resolution, and senescent cell elimination.

3D bioprinting using a new photo-crosslinking method for muscle tissue restoration

Three-dimensional (3D) bioprinting is a highly effective technique for fabricating cell-loaded constructs in tissue engineering. However, the versatility of fabricating precise and complex cell-loaded hydrogels is limited owing to the poor crosslinking ability of cell-containing hydrogels. Herein, we propose an optic-fiber-assisted bioprinting (OAB) process to efficiently crosslink methacrylated hydrogels. By selecting appropriate processing conditions for the photo-crosslinking technique, we fabricated biofunctional cell-laden structures including methacrylated gelatin (Gelma), collagen, and decellularized extracellular matrix. To apply the method to skeletal muscle regeneration, cell-laden Gelma constructs were processed with a functional nozzle having a topographical cue and an OAB process that could induce a uniaxial alignment of C2C12 and human adipose stem cells (hASCs). Significantly higher degrees of cell alignment and myogenic activities in the cell-laden Gelma structure were observed compared with those in the cell construct that was printed using a conventional crosslinking method. Moreover, an in vivo regenerative potential was observed in volumetric muscle defects in a mouse model. The hASC-laden construct significantly induced greater muscle regeneration than the cell construct without topographical cues. Based on the results, the newly designed bioprinting process can prove to be highly effective in fabricating biofunctional cell-laden constructs for various tissue engineering applications.

Signaling pathways of adipose stem cell-derived exosomes promoting muscle regeneration

ABSTRACT

Severe muscle injury is still a challenging clinical problem. Exosomes derived from adipose stem cells (ASC-exos) may be a potential therapeutic tool, but their mechanism is not completely clear. This review aims to elaborate the possible mechanism of ASC-exos in muscle regeneration from the perspective of signal pathways and provide guidance for further study. Literature cited in this review was acquired through PubMed using keywords or medical subject headings, including adipose stem cells, exosomes, muscle regeneration, myogenic differentiation, myogenesis, wingless/integrated (Wnt), mitogen-activated protein kinases, phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B (PI3K/Akt), Janus kinase/signal transducers and activators of transcription, and their combinations. We obtained the related signal pathways from proteomics analysis of ASC-exos in the literature, and identified that ASC-exos make different contributions to multiple stages of skeletal muscle regeneration by those signal pathways.

The regenerative potential of Pax3/Pax7 on skeletal muscle injury

Background

Skeletal muscle mishaps are the most well-known incidents in society, especially among athletes and the military population. From the various urgency, this accident needs to be cured more quickly. However, the current treatment still has some shortcomings and is less effective. In this case, Paired box 3 and Paired box 7 (Pax3/Pax7) proteins that induce stem cells could potentially be an alternative treatment for skeletal muscle injuries. This paper aimed to analyse the potential treatment of Pax3/Pax7 proteins inducing the stem cell for skeletal muscle injuries.

The main body of the abstract

We did a narrative review by gathering several scientific journals from several leading platforms like PubMed and Scopus. As common accidents, skeletal muscle disease could be due to workplace and non-workplace causes. The highest risk occurs in the athlete and military environment. The treatment of current skeletal muscle injuries is protection, rest, ice, compression, and elevation (PRICE), non-steroidal anti-inflammatory drugs (NSAIDs), and mechanical stimulation. However, it is considered less effective, especially in NSAIDs, inhibiting myogenic cell proliferation. The current finding indicates that the stem cells have markers known as Pax3/Pax7. The role of both markers in muscle injury, Pax3/Pax7, as transcription factors will induce cell division by H3K4 methylation mechanisms and chromatin modifications that stimulate gene activation.

Conclusion

Regulation by Pax3/Pax7 factors that affect stem cells and stem cell proliferation is one of the alternative treatments. This regulation can accelerate the healing of injury victims, especially injuries to the skeletal muscles. Finally, after being compared, Pax3/Pax7 induces stem cells to have the potential to be one of the skeletal muscle injury treatments.

Keywords

Pax3 and Pax7, Pax3/Pax7, Skeletal muscle, Athlete, Stem cells, Cell proliferation, Injuries.

Preclinical research studies for treating severe muscular injuries: focus on tissue-engineered strategies

Severe skeletal muscle injuries are a lifelong trauma with limited medical solutions. Significant progress has been made in developing in vitro surrogates for treating such trauma. However, more attention is needed when translating these approaches to the clinic. In this review, we survey the potential of tissue-engineered surrogates in promoting muscle healing, by critically analyzing data from recent preclinical models. The therapeutic advantages provided by a combination of different biomaterials, cell types, and biochemical mediators are discussed. Current therapies on muscle healing are also summarized, emphasizing their main advantages and drawbacks. We also discuss previous and ongoing clinical trials as well as highlighting future directions for the field.

Redesigning of 3-Dimensional Vascular-Muscle Structure Using ADSCs/HUVECs Co-Culture and VEGF on Engineered Skeletal Muscle ECM

OBJECTIVE

The main objective of this study is to determine the myogenic effects of skeletal muscle extracellular matrix, vascular endothelial growth factor and human umbilical vein endothelial cells on adipose-derived stem cells to achieve a 3-dimensional engineered vascular-muscle structure.

MATERIALS AND METHODS

The present experimental research was designed based on two main groups, i.e. monoculture of adipose tissue-derived stem cells (ADSCs) and co-culture of ADSCs and human umbilical vein endothelial cells (HUVECs) in a ratio of 1:1. Skeletal muscle tissue was isolated, decellularized and its surface was electrospun using polycaprolactone/gelatin parallel nanofibers and then matrix topography was evaluated through H and E, trichrome staining and SEM. The expression of MyHC2 gene and tropomyosin protein were examined through real-time reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence, respectively. Finally, the morphology of mesenchymal and endothelial cells and their relationship with each other and with the engineered scaffold were examined by scanning electron microscopy (SEM).

RESULTS

According to H and E and Masson's Trichrome staining, muscle tissue was completely decellularized. SEM showed parallel Polycaprolactone (PCL)/gelatin nanofibers with an average diameter of about 300 nm. The immunofluorescence proved that tropomyosin was positive in the ADSCs monoculture and the ADSCs/HUVECs coculture in horse serum (HS) and HS/VEGF groups. There was a significant difference in the expression of the MyHC2 gene between the ADSCs and ADSCs/HUVECs culture groups (P<0.05) and between the 2D and 3D models in HS/ VEGF differentiation groups (P<001). Moreover, a significant increase existed between the HS/VEGF group and other groups in terms of endothelial cells growth and proliferation as well as their relationship with differentiated myoblasts (P<0.05).

CONCLUSION

Co-culture of ADSCs/HUVECs on the engineered cell-free muscle scaffold and the dual effects of VEGF can lead to formation of a favorable engineered vascular-muscular tissue. These engineered structures can be used as an acceptable tool for tissue implantation in muscle injuries and regeneration, especially in challenging injuries such as volumetric muscle loss, which also require vascular repair.

N6-Methyladenosine RNA Modification: A Potential Regulator of Stem Cell Proliferation and Differentiation

Stem cell transplantation (SCT) holds great promise for overcoming diseases by regenerating damaged cells, tissues and organs. The potential for self-renewal and differentiation is the key to SCT. RNA methylation, a dynamic and reversible epigenetic modification, is able to regulate the ability of stem cells to differentiate and regenerate. N⁶-methyladenosine (m⁶A) is the richest form of RNA methylation in eukaryotes and is regulated by three classes of proteins: methyltransferase complexes, demethylase complexes and m⁶A binding proteins. Through the coordination of these proteins, RNA methylation precisely modulates the expression of important target genes by affecting mRNA stability, translation, selective splicing, processing and microRNA maturation. In this review, we summarize the most recent findings on the regulation of m⁶A modification in embryonic stem cells, induced pluripotent stem cells and adult stem cells, hoping to provide new insights into improving SCT technology.

Dynamics of the development of subcutaneous fat depots in rabbits – a gross anatomical and microscopic study

In this study, gross anatomical and microscopic features of interscapular (IsFD) and inguinal (InFD) fat depots of 24 New Zealand White rabbits were evaluated. Rabbits were equally distributed into 4 groups: 1st - newborns, 2nd - 1 month old, 3rd - 2 months old and 4th - 3 months old. The cranial subcutaneous fat pad in newborns covered dorsal and ventral cervical and interscapular regions. As age advanced, cervical lobes underwent a rapid reduction but the development of interscapular lobes continued. IsFD in rabbits from 1st and 2nd group was composed of both white and brown adipocytes, while in 3rd and 4th groups it consisted of white adipocytes only. InFD in rabbits from all tested groups occupied respective inguinal region and no age-dependent changes in shape and topography were observed. In all groups InFD was composed of white adipocytes only. The highest growth rate of interscapular and inguinal adipocytes was established in one-month-old rabbits. Differences in anatomy and histology of interscapular and inguinal fat depots in rabbits could be successfully used for comparison in other experiments in the field of adipobiology and autologous transplantation, where fat depots undergo significant morphological changes.

Skeletal Muscle Regeneration by the Exosomes of Adipose Tissue-Derived Mesenchymal Stem Cells

Profound skeletal muscle loss can lead to severe disability and cosmetic deformities. Mesenchymal stem cell (MSC)-derived exosomes have shown potential as an effective therapeutic tool for tissue regeneration. This study aimed to determine the regenerative capacity of MSC-derived exosomes for skeletal muscle regeneration. Exosomes were isolated from human adipose tissue-derived MSCs (AD-MSCs). The effects of MSC-derived exosomes on satellite cells were investigated using cell viability, relevant genes, and protein analyses. Moreover, NOD-SCID mice were used and randomly assigned to the healthy control (n = 4), muscle defect (n = 6), and muscle defect + exosome (n = 6) groups. Muscle defects were created using a biopsy punch on the quadriceps of the hind limb. Four weeks after the surgery, the quadriceps muscles were harvested, weighed, and histologically analyzed. MSC-derived exosome treatment increased the proliferation and expression of myocyte-related genes, and immunofluorescence analysis for myogenin revealed a similar trend. Histologically, MSC-derived exosome-treated mice showed relatively preserved shapes and sizes of the muscle bundles. Immunohistochemical staining revealed greater expression of myogenin and myoblast determination protein 1 in the MSC-derived exosome-treated group. These results indicate that exosomes extracted from AD-MSCs have the therapeutic potential for skeletal muscle regeneration.

The biological applications of DNA nanomaterials: current challenges and future directions

DNA, a genetic material, has been employed in different scientific directions for various biological applications as driven by DNA nanotechnology in the past decades, including tissue regeneration, disease prevention, inflammation inhibition, bioimaging, biosensing, diagnosis, antitumor drug delivery, and therapeutics. With the rapid progress in DNA nanotechnology, multitudinous DNA nanomaterials have been designed with different shape and size based on the classic Watson-Crick base-pairing for molecular self-assembly. Some DNA materials could functionally change cell biological behaviors, such as cell migration, cell proliferation, cell differentiation, autophagy, and anti-inflammatory effects. Some single-stranded DNAs (ssDNAs) or RNAs with secondary structures via self-pairing, named aptamer, possess the ability of targeting, which are selected by systematic evolution of ligands by exponential enrichment (SELEX) and applied for tumor targeted diagnosis and treatment. Some DNA nanomaterials with three-dimensional (3D) nanostructures and stable structures are investigated as drug carrier systems to delivery multiple antitumor medicine or gene therapeutic agents. While the functional DNA nanostructures have promoted the development of the DNA nanotechnology with innovative designs and preparation strategies, and also proved with great potential in the biological and medical use, there is still a long way to go for the eventual application of DNA materials in real life. Here in this review, we conducted a comprehensive survey of the structural development history of various DNA nanomaterials, introduced the principles of different DNA nanomaterials, summarized their biological applications in different fields, and discussed the current challenges and further directions that could help to achieve their applications in the future.

Skeletal muscle regeneration with robotic actuation-mediated clearance of neutrophils

[Figure: see text].

Bio-printing of aligned GelMa-based cell-laden structure for muscle tissue regeneration

Volumetric muscle loss (VML) is associated with a severe loss of muscle tissue that overwhelms the regenerative potential of skeletal muscles. Tissue engineering has shown promise for the treatment of VML injuries, as evidenced by various preclinical trials. The present study describes the fabrication of a cell-laden GelMa muscle construct using an in situ crosslinking (ISC) strategy to improve muscle functionality. To obtain optimal biophysical properties of the muscle construct, two UV exposure sources, UV exposure dose, and wall shear stress were evaluated using C2C12 myoblasts. Additionally, the ISC system showed a significantly higher degree of uniaxial alignment and myogenesis compared to the conventional crosslinking strategy (post-crosslinking). To evaluate the in vivo regenerative potential, muscle constructs laden with human adipose stem cells were used. The VML defect group implanted with the bio-printed muscle construct showed significant restoration of functionality and muscular volume. The data presented in this study suggest that stem cell-based therapies combined with the modified bioprinting process could potentially be effective against VML injuries.

Role of Vascular Endothelial Growth Factor and Human Umbilical Vein Endothelial Cells in Designing An In Vitro Vascular-Muscle Cellular Model Using Adipose-Derived Stem Cells

Objective

Researchers have been interested in the creation of a favorable cellular model for use in vascular-muscle tissue engineering. The main objective of this study is to determine the myogenic effects of vascular endothelial growth factor (VEGF) and human umbilical vein endothelial cells (HUVECs) on adipose-derived stem cells (ADSCs) to achieve an in vitro vascular-muscle cellular model.

Materials and Methods

The present experimental research was conducted on two primary groups, namely ADSCs monoculture and ADSCs/HUVECs co-culture that were divided into control, horse serum (HS), and HS/VEGF differentiation subgroups. HUVECs were co-cultured by ADSC in a ratio of 1:1. The myogenic differentiation was evaluated using the reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence in different experimental groups. The interaction between ADSCs and HUVECs, as well as the role of ADSCs conditional medium, was investigated for endothelial tube formation assay.

Results

Immunofluorescence staining indicated that Tropomyosin was positive in ADSCs and ADSCs and HUVECs co-culture groups on HS and HS/VEGF culture medium. Furthermore, the MyHC2 gene expression significantly increased in HS and HS/VEGF groups in comparison with the control group (P<0.001). More importantly, there was a significant difference in the mRNA expression of this gene between ADSCs and ADSCs and HUVECs co-culture groups on HS/VEGF culture medium (P<0.05). Current data revealed that the co-culture of ADSCs and HUVECs could develop endothelial network formation in the VEGF-loaded group. Also, the ADSCs-conditioned medium improved the viability and formation of the endothelial tube in the HS and VEGF groups, respectively.

Conclusion

It was concluded that ADSCs/HUVECs co-culture and dual effects of VEGF can lead to the formation of differentiated myoblasts in proximity to endothelial network formations. These in vitro cellular models could be potentially used in vascular-muscle tissue engineering implanted into organ defects where muscle tissue and vascular regeneration were required.

Effects of ASC Application on Endplate Regeneration Upon Glycerol-Induced Muscle Damage

Amongst other approaches, adipose-derived stromal cells (ASCs) have recently been tested with respect to their regenerative capacity for treatment of neuromuscular disorders. While beneficial effects of ASCs on muscle recovery were observed previously, their impact on regeneration of neuromuscular junctions (NMJs) is unclear. Here, we used a murine glycerol damage model to study disruption and regeneration of NMJs and to evaluate the effects of systemic application of ASCs on muscle and NMJ recovery. In mice that were not treated with ASCs, a differential response of NMJ pre- and post-synapses to glycerol-induced damage was observed. While post-synapses were still present in regions that were necrotic and lacking actin and dystrophin, pre-synapses disappeared soon in those affected areas. Partial regeneration of NMJs occurred within 11 days after damage. ASC treatment slightly enhanced NMJ recovery and reduced the loss of presynaptic sites, but also led to a late phase of muscle necrosis and fibrosis. In summary, the results suggest a differential sensitivity of NMJ pre- and post-synapses to glycerol-induced muscle damage and that the use of ASC for the treatment of neuromuscular disorders needs further careful evaluation.

Inhibitory effect of red LED irradiation on fibroblasts and co-culture of adipose-derived mesenchymal stem cells

The objective of this study was to evaluate the effects of red Light Emiting Diode (red LED) irradiation on fibroblasts in adipose-derived mesenchymal stem cells (ASC) co-culture on the scratch assay. We hypothesized that red LED irradiation could stimulate paracrine secretion of ASC, contributing to the activation of genes and molecules involved in cell migration and tissue repair. ASC were co-cultured with NIH/3T3 fibroblasts through direct contact and subjected to red LED irradiation (1.45 J/cm²/5min6s) after the scratch assay, during 4 days. Four groups were established: fibroblasts (F), fibroblasts + LED (FL), fibroblasts + ASC (FC) and fibroblasts + LED + ASC (FLC). The analyzes were based on Ctgf and Reck expression, quantification of collagen types I and III, tenomodulin, VEGF, TGF-β1, MMP-2 and MMP-9, as well as viability analysis and cell migration. Higher Ctgf expression was observed in FC compared to F. Group FC presented higher amount of tenomodulin and VEGF in relation to the other groups. In the cell migration analysis, a higher number of cells was observed in the scratched area of the FC group on the 4^th day. There were no differences between groups considering cell viability, Reck expression, amount of collagen types I and III, MMP-2 and TGF-β1, whereas TGF-β1 was not detected in the FC group and the MMP-9 in none of the groups. Our hypothesis was not supported by the results because the red LED irradiation decreased the healing response of ASC. An inhibitory effect of the LED irradiation associated with ASC co-culture was observed with reduction of the amount of TGF-β1, VEGF and tenomodulin, possibly involved in the reduced cell migration. In turn, the ASC alone seem to have modulated fibroblast behavior by increasing Ctgf, VEGF and tenomodulin, leading to greater cell migration. In conclusion, red LED and ASC therapy can have independent effects on fibroblast wound healing, but the combination of both does not have a synergistic effect. Therefore, future studies with other parameters of red LED associated with ASC should be tested aiming clinical application for tissue repair.

Histology of skeletal muscle reconstructed by means of the implantation of autologous adipose tissue: an experimental study

The purpose of this study was to determine the histological characteristics of a skeletal muscle reconstructed by means of the implantation of autologous adipose tissue following an experimentally-induced volumetric muscle loss. A cylindrical piece in the belly of the rat anterior tibial muscle was removed. In the hole, inguinal subcutaneous adipose tissue of the same rat was grafted. Animals were sacrificed 7, 14, 21, 28 and 60 days posttransplantation. Histological, histochemical, immunohistochemical and morphometric techniques were used. At all times analyzed, the regenerative muscle fibers formed from the edges of the muscle tissue showed histological, histochemical and immunohistochemical differences in comparison with the control group. These differences are related to delays in the maturation process and are related to problems in reinnervation and disorientation of muscle fibers. The stains for MyoD and desmin showed that some myoblasts and myotubes seem to derive from the transplanted adipose tissue. After 60 days, the transplant area was 20% occupied by fibrosis and by 80% skeletal muscle. However, the neo-muscle was chaotically organized showing muscle fiber disorientation and centronucleated fibers with irregular shape and size. Our results support the hypothesis that, at least from a morphological point of view, autologous adipose tissue transplantation favors reconstruction following a volumetric loss of skeletal muscle by combining the inherent regenerative response of the organ itself and the myogenic differentiation of the stem cells present in the adipose tissue. However, in our study, the formed neo-muscle exhibited histological differences in comparison with the normal skeletal muscle.

Application of Bone Marrow-Derived Mesenchymal Stem Cells for Muscle Healing After Contusion Injury in Mice

BACKGROUND

Skeletal muscle injuries are very common in sports medicine. Conventional therapies have limited clinical efficacy. New treatment methods should be developed to allow athletes to return to play with better function.

PURPOSE

To evaluate the in vitro differentiation potential of bone marrow-derived mesenchymal stem cells and the in vivo histologic and physiologic effects of mesenchymal stem cell therapy on muscle healing after contusion injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bone marrow cells were flushed from both femurs of 5-week-old C57BL/6 mice to establish immortalized mesenchymal stem cell lines. A total of 36 mice aged 8 to 10 weeks were used to develop a muscle contusion model and were divided into 6 groups (6 mice/group) on the basis of the different dosages of IM2 cells to be injected (0, 1.25 × 105, and 2.5 × 105 cells with/without F-127 in 100 μL of phosphate-buffered saline). Histological analysis of muscle regeneration was performed, and the fast-twitch and tetanus strength of the muscle contractions was measured 28 days after muscle contusion injury, after injections of different doses of mesenchymal stem cells with or without the F-127 scaffold beginning 14 days after contusion injury.

RESULTS

The mesenchymal stem cell-treated muscles exhibited numerous regenerating myofibers. All the groups treated with mesenchymal stem cells (1.25 × 105 cells, 2.5 × 105 cells, 1.25 × 105 cells plus F-127, and 2.5 × 105 cells plus F-127) exhibited a significantly higher number of regenerating myofibers (mean ± SD: 111.6 ± 14.77, 133.4 ± 21.44, 221.89 ± 32.65, and 241.5 ± 25.95, respectively) as compared with the control group and the control with F-127 (69 ± 18.79 and 63.2 ± 18.98). The physiologic evaluation of fast-twitch and tetanus strength did not reveal differences between the age-matched uninjured group and the groups treated with various doses of mesenchymal stem cells 28 days after contusion. Significant differences were found between the control group and the groups treated with various doses of mesenchymal stem cells after muscle contusion.

CONCLUSION

Mesenchymal stem cell therapy increased the number of regenerating myofibers and improved fast-twitch and tetanus muscle strength in a mouse model of muscle contusion. However, the rapid decay of transplanted mesenchymal stem cells suggests a paracrine effect of this action. Treatment with mesenchymal stem cells at various doses combined with the F-127 scaffold is a potential therapy for a muscle contusion.

CLINICAL RELEVANCE

Mesenchymal stem cell therapy has an effect on sports medicine because of its effects on myofiber regeneration and muscle strength after contusion injury.

Recent advances toward understanding the role of transplanted stem cells in tissue-engineered regeneration of musculoskeletal tissues

Stem cell-based tissue engineering is poised to revolutionize the treatment of musculoskeletal injuries. However, in order to overcome scientific, practical, and regulatory obstacles and optimize therapeutic strategies, it is essential to better understand the mechanisms underlying the pro-regenerative effects of stem cells. There has been an attempted paradigm shift within the last decade to think of transplanted stem cells as "medicinal" therapies that orchestrate healing on the basis of their secretome and immunomodulatory profiles rather than acting as bona fide stem cells that proliferate, differentiate, and directly produce matrix to form de novo tissues. Yet the majority of current bone and skeletal muscle tissue engineering strategies are still premised on a direct contribution of stem cells as building blocks to tissue regeneration. Our review of the recent literature finds that researchers continue to focus on the quantification of de novo bone/skeletal muscle tissue following treatment and few studies aim to address this mechanistic conundrum directly. The dichotomy of thought is reflected in the diversity of new advances ranging from in situ three-dimensional bioprinting to a focus on exosomes and extracellular vesicles. However, recent findings elucidating the role of the immune system in tissue regeneration combined with novel imaging platform technologies will have a profound impact on our future understanding of how stem cells promote healing following biomaterial-mediated delivery to defect sites.

Adipose-Derived Mesenchymal Stem Cells: A Promising Tool in the Treatment of Musculoskeletal Diseases

Chronic musculoskeletal (MSK) pain is one of the most common medical complaints worldwide and musculoskeletal injuries have an enormous social and economical impact. Current pharmacological and surgical treatments aim to relief pain and restore function; however, unsatiscactory outcomes are commonly reported. In order to find an accurate treatment to such pathologies, over the last years, there has been a significantly increasing interest in cellular therapies, such as adipose-derived mesenchymal stem cells (AMSCs). These cells represent a relatively new strategy in regenerative medicine, with many potential applications, especially regarding MSK disorders, and preclinical and clinical studies have demonstrated their efficacy in muscle, tendon, bone and cartilage regeneration. Nevertheless, several worries about their safety and side effects at long-term remain unsolved. This article aims to review the current state of AMSCs therapy in the treatment of several MSK diseases and their clinical applications in veterinary and human medicine.

Autologous decellularized extracellular matrix protects against H2O2-induced senescence and aging in adipose-derived stem cells and stimulates proliferation in vitro

Background: Adipose-derived stem cells have attracted significant interest, especially in stem cell therapy and regenerative medicine. However, these cells undergo gradual premature senescence in long-term cultures, which are essential for clinical applications that require cell-assisted lipotransfer or tissue repair. Methods: Since the extracellular matrix forms the microenvironment around stem cells in vitro and regulates self-renewal and multipotency in part by slowing down stem cell aging, we evaluated its potential to protect against senescence, using H₂O₂-induced adipose-derived stem cells as a model. Results: We found that supplementing cultures with decellularized extracellular matrix harvested from the same cells significantly promotes proliferation and reverses signs of senescence, including decreased multipotency, increased expression of senescence-associated β-galactosidase, and accumulation of reactive oxygen species. Conclusion: These findings suggest a novel approach in which an autologous decellularized extracellular matrix is used to prevent cellular senescence to enable the use of adipose-derived stem cells in regenerative medicine.

Co-transplantation of mesenchymal stem cells improves spermatogonial stem cell transplantation efficiency in mice

Background

Spermatogonial stem cell transplantation (SSCT) could become a fertility restoration tool for childhood cancer survivors. However, since in mice, the colonization efficiency of transplanted spermatogonial stem cells (SSCs) is only 12%, the efficiency of the procedure needs to be improved before clinical implementation is possible. Co-transplantation of mesenchymal stem cells (MSCs) might increase colonization efficiency of SSCs by restoring the SSC niche after gonadotoxic treatment.

Methods

A mouse model for long-term infertility was developed and used to transplant SSCs (SSCT, n = 10), MSCs (MSCT, n = 10), a combination of SSCs and MSCs (MS-SSCT, n = 10), or a combination of SSCs and TGFß1-treated MSCs (MSi-SSCT, n = 10).

Results

The best model for transplantation was obtained after intraperitoneal injection of busulfan (40 mg/kg body weight) at 4 weeks followed by CdCl₂ (2 mg/kg body weight) at 8 weeks of age and transplantation at 11 weeks of age. Three months after transplantation, spermatogenesis resumed with a significantly better tubular fertility index (TFI) in all transplanted groups compared to non-transplanted controls (P < 0.001). TFI after MSi-SSCT (83.3 ± 19.5%) was significantly higher compared to MS-SSCT (71.5 ± 21.7%, P = 0.036) but did not differ statistically compared to SSCT (78.2 ± 12.5%). In contrast, TFI after MSCT (50.2 ± 22.5%) was significantly lower compared to SSCT (P < 0.001). Interestingly, donor-derived TFI was found to be significantly improved after MSi-SSCT (18.8 ± 8.0%) compared to SSCT (1.9 ± 1.1%; P < 0.001), MSCT (0.0 ± 0.0%; P < 0.001), and MS-SSCT (3.4 ± 1.9%; P < 0.001). While analyses showed that both native and TGFß1-treated MSCs maintained characteristics of MSCs, the latter showed less migratory characteristics and was not detected in other organs.

Conclusion

Co-transplanting SSCs and TGFß1-treated MSCs significantly improves the recovery of endogenous SSCs and increases the homing efficiency of transplanted SSCs. This procedure could become an efficient method to treat infertility in a clinical setup, once the safety of the technique has been proven.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1065-0) contains supplementary material, which is available to authorized users.

Adipose Stem Cell Translational Applications: From Bench-to-Bedside

During the last five years, there has been a significantly increasing interest in adult adipose stem cells (ASCs) as a suitable tool for translational medicine applications. The abundant and renewable source of ASCs and the relatively simple procedure for cell isolation are only some of the reasons for this success. Here, we document the advances in the biology and in the innovative biotechnological applications of ASCs. We discuss how the multipotential property boosts ASCs toward mesenchymal and non-mesenchymal differentiation cell lineages and how their character is maintained even if they are combined with gene delivery systems and/or biomaterials, both in vitro and in vivo.