Lancet Commission: Stem cells and regenerative medicine

SDF-1α/BMP-12 loaded biphasic sustained-release SIS hydrogel/SA microspheres composite for tendon regeneration

Due to the inherent limited regenerative capacity of tendons, rendering countermeasures for tendon injury remains challenging. The pathophysiology of tendon healing is complex and contains three sequential phases including inflammation, proliferation and remodeling. Aiming at the treatment of different stages of tendon injury, in our work, an injectable small intestinal submucosa hydrogel/sodium alginate microspheres (SIS/SA) composite co-encapsulating stromal cell derived factor-1α (SDF-1α) and bone morphogenetic protein-12 (BMP-12) was developed for effective tendon regeneration. BMP-12 was initially embedded into SA microspheres by microfluid method, and then, microspheres were subsequently encapsulated into the SDF-1α loaded SIS hydrogel. The two bioactive molecules were released in a biphasic and controlled manner to facilitate cell recruitment in the early stage and tendon differentiation in the long-time stage, respectively. Meanwhile, with the degradation of hydrogel/microspheres composite, the regeneration process was accelerated through multiple pathways encompassing immune regulation, angiogenesis, and extracellular matrix (ECM) synthesis. The findings of this study present a compelling translational strategy with significant clinical potential for advancing tendon regeneration therapies.

Hydrogels with programmed spatiotemporal mechanical cues for stem cell-assisted bone regeneration

Hydrogels are extensively utilized in stem cell-based tissue regeneration, providing a supportive environment that facilitates cell survival, differentiation, and integration with surrounding tissues. However, designing hydrogels for regenerating hard tissues like bone presents significant challenges. Here, we introduce macroporous hydrogels with spatiotemporally programmed mechanical properties for stem cell-driven bone regeneration. Using liquid-liquid phase separation and interfacial supramolecular self-assembly of protein fibres, the macroporous structure of hydrogels provide ample space to prevent contact inhibition during proliferation. The rigid protein fibre-coated pore shell provides sustained mechanical cues for guiding osteodifferentiation and protecting against mechanical loads. Temporally, the hydrogel exhibits tunable degradation rates that can synchronize with new tissue deposition to some extent. By integrating localized mechanical heterogeneity, macroporous structures, surface chemistry, and regenerative degradability, we demonstrate the efficacy of these stem cell-encapsulated hydrogels in rabbit and porcine models. This marks a substantial advancement in tailoring the mechanical properties of hydrogels for stem cell-assisted tissue regeneration.

Development of regenerative therapies targeting fibrotic endometrium in intrauterine adhesion or thin endometrium to restore uterine function

Intrauterine adhesions (IUA) and thin endometrium (TE) represent significant challenges in human reproduction. The condition arises frequently from damage to the endometrial basal layer, leading to fibrous tissue replacing the functional endometrium and impairing the uterus's ability to accept embryo implantation. Conventional treatments, mainly including hysteroscopic adhesiolysis and estrogen therapies, have shown limited success, particularly in severe cases. Regenerative medicine, with its focus on stem cell-based therapies and biomaterials, offers a promising avenue for restoring endometrial function and structure. This review synthesizes the current landscape of endometrial regeneration, focusing on the therapeutic potential of stem cells, the supportive role of biomaterials, and the importance of understanding molecular mechanisms to develop effective strategies for reconstruction of endometrial functional and fertility restoration.

Protective effects of silk fibroin against 6-OHDA in SH-SY5Y human neuroblastoma cells and comparative study with its release from gelatin films

In this study, we analyzed the neuroprotective action of silk fibroin (SF) regenerated with calcium chloride (CaCl2), distinguishing the effects of CaCl2 and SF, and subsequently fabricating a neuroprotective hybrid material based on SF gelatin film. Cytotoxicity induced by 6-hydroxydopamine (6-OHDA) on the human neuroblastoma SH-SY5Y cell line showed that SF had a significant shielding power against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in SH-SY5Y neuroblastoma cells, as assessed by the CCK-8 assay, cell imaging and cell cycle using flow cytometer. Specifically, the concurrent treatment with SF and 6-OHDA produced a marked neuroprotective effect. Circular dichroism analysis suggested the formation of silk III because of the interaction between the secondary structures of SF and 6-OHDA. Raman analysis was also employed to assess the impact of SF and CaCl2 on cellular metabolism, indicating the combined administration of fibroin and 6-OHDA as more effective than the use of CaCl2 alone. Subsequently, we synthesized a silk/gelatin-based film, demonstrated its ability to release SF, and confirmed its capacity to protect SH-SY5Y neuroblastoma cells.

Orthobiologic therapies delay the need for hip arthroplasty in patients with avascular necrosis of the femoral head: A systematic review and survival analysis

PURPOSE

The aim of this systematic review and survival analysis was to quantify the benefits of orthobiologic augmentation therapies for the treatment of avascular necrosis (AVN) of the femoral head and identify the most effective approach to delay the need for total hip arthroplasty (THA).

METHODS

A systematic review of the literature was performed on PubMed, Scopus, and Cochrane on clinical studies on orthobiologic therapies used alone or as an augmentation to core decompression or other procedures to address hip AVN. A qualitative analysis of the different biological therapies applied was performed. Afterward, the results of these procedures were quantitatively analysed to document their survivorship from THA compared to treatment groups without orthobiologics. Kaplan-Meier analysis was performed for all studies and then by categorising orthobiologics into treatment subgroups.

RESULTS

A total of 106 studies were included (4505 patients). Different orthobiologic approaches have been evaluated: cell-based therapies including bone marrow aspirate concentrate (BMAC) and bone marrow mesenchymal stromal cells (BM-MSCs), platelet-rich plasma (PRP), or other bioactive molecules applied in the osteonecrotic area or as intra-arterial injections. The survival analysis at 120 months documented a higher (p < 0.0005) cumulative survivorship with orthobiologics (69.4%) compared to controls (48.5%). The superiority was shown specifically for BMAC (p < 0.0005), BM-MSCs (p < 0.0005), intra-arterial (p < 0.0005) and PRP (p = 0.011) approaches, but the direct comparison of these approaches with their controls confirmed benefits only for BMAC (p < 0.0005).

CONCLUSION

This systematic review and survival analysis demonstrated that orthobiologics have the potential to improve survivorship in patients affected by hip AVN. In particular, the specific analysis of different orthobiologic products supported relevant benefits for BMAC augmentation in terms of survival from the need for THA, while no clear benefits were confirmed for other orthobiologics.

LEVEL OF EVIDENCE

Level III.

The role of oxidative stress-mediated fibro-adipogenic progenitor senescence in skeletal muscle regeneration and repair

BACKGROUND

Stem cells play a pivotal role in tissue regeneration and repair. Skeletal muscle comprises two main stem cells: muscle stem cells (MuSCs) and fibro-adipogenic progenitors (FAPs). FAPs are essential for maintaining the regenerative milieu of muscle tissue and modulating the activation of muscle satellite cells. However, during acute skeletal muscle injury, the alterations and mechanisms of action of FAPs remain unclear.

METHODS

we employed the GEO database for bioinformatics analysis of skeletal muscle injury. A skeletal muscle injury model was established through cardiotoxin (CTX, 10µM, 50µL) injection into the tibialis anterior (TA) of C57BL/6 mice. Three days post-injury, we extracted the TA, isolated FAPs (CD31-CD45-PDGFRα+Sca-1+), and assessed the senescence phenotype through SA-β-Gal staining and Western blot. Additionally, we established a co-culture system to evaluate the capacity of FAPs to facilitate MuSCs differentiation. Finally, we alleviated the senescent of FAPs through in vitro (100 µM melatonin, 5 days) and in vivo (20 mg/kg/day melatonin, 15 days) administration experiments, confirming melatonin's pivotal role in the regeneration and repair processes of skeletal muscle.

RESULTS

In single-cell RNA sequencing analysis, we discovered the upregulation of senescence-related pathways in FAPs following injury. Immunofluorescence staining revealed the co-localization of FAPs and senescent markers in injured muscles. We established the CTX injury model and observed a reduction in the number of FAPs post-injury, accompanied by the manifestation of a senescent phenotype. Melatonin treatment was found to attenuate the injury-induced senescence of FAPs. Further co-culture experiments revealed that melatonin facilitated the restoration of FAPs' capacity to promote myoblast differentiation. Through GO and KEGG analysis, we found that the administration of melatonin led to the upregulation of AMPK pathway in FAPs, a pathway associated with antioxidant stress response. Finally, drug administration experiments corroborated that melatonin enhances skeletal muscle regeneration and repair by alleviating FAP senescence in vivo.

CONCLUSION

In this study, we first found FAPs underwent senescence and redox homeostasis imbalance after injury. Next, we utilized melatonin to enhance FAPs regenerative and repair capabilities by activating AMPK signaling pathway. Taken together, this work provides a novel theoretical foundation for treating skeletal muscle injury.

Porcine pericardial decellularized matrix bilayer patch containing adipose stem cell-derived exosomes for the treatment of diabetic wounds

Chronic hard-to-heal wounds pose a significant threat to patients' health and quality of life, and their clinical management remains a challenge. Adipose-derived stem cell exosomes (ADSC-exos) have shown promising results in promoting diabetic wound healing. However, effectively enhancing the retention of exosomes in wounds for treatment remains a key issue that needs to be addressed. There is a pressing need to develop new materials or methods to improve the bioavailability of exosomes. Porcine pericardium, an extracellular matrix-rich tissue, is easily obtainable and widely available. Decellularized porcine pericardium removes cellular components while retaining an extracellular matrix that supports cellular growth, making it an ideal raw material for preparing wound dressings. In this study, we developed porcine pericardial decellularized matrix bilayer patches loaded with ADSC-exos, which were transplanted into diabetic mouse skin wounds. Histological and immunohistochemical analyses revealed that these bilayer matrix patches accelerate wound healing by promoting granulation tissue formation, re-epithelialization, stimulating vascularization, and enhancing collagen production. In terms of the underlying biological mechanism, we found that decellularized extracellular matrix bilayer patches loaded with ADSC-exos enhanced the proliferation and migration of human dermal fibroblasts (HDFs) and HaCaT cells in vitro, and promoted tube formation in human umbilical vein endothelial cells (HUVECs). This research demonstrated that the porcine pericardial decellularized matrix is well-suited for exosome delivery and that these bilayer patches hold great potential in promoting diabetic wound healing, providing evidence to support the future clinical application of ADSC-exos.

Mutanobactin-D, a Streptococcus mutans Non-Ribosomal Cyclic Lipopeptide, Induces Osteogenic/Odontogenic Differentiation of Human Dental Pulp Stem Cells and Human Bone Marrow Stem Cells

Bacterium-triggered carious lesions implicate dental hard tissue destruction and the simultaneous initiation of regenerative events comprising dental stem cell activation. Streptococcus mutans (S. mutans) is a prominent pathogen of the oral cavity and the principal cause of caries. S. mutans generates complex products involved in interbacterial interactions, including Mutanobactin-D (Mub-D), which belongs to a group of non-ribosomal cyclic lipopeptides. In the present study, we aimed to analyse the potential role of the synthetic Mub-D peptide in cell populations involved in tissue regenerative processes. To this end, we assessed the in vitro effects of Mub-D in human dental pulp stem cells (hDPSCs) and human bone marrow stem cells (hBMSCs). Our data demonstrated a concentration-dependent effect of Mub-D on their viability and a significant increase in their proliferation and osteogenic/odontogenic differentiation. These events were associated with specific changes in gene expression, where CCDN-1, RUNX-2, OSX, OCN, DMP-1, DSPP, and BMP-2 genes were upregulated. The ability of Mub-D to modulate the osteogenic/odontogenic differentiation of both hDPSCs and hBMSCs and considerably enhance mineralisation in a controlled and concentration-dependent manner opens new perspectives for stem cell-based regenerative approaches in the clinics.

What is known about healthcare professional-patient communication when discussing stem cell therapies? A scoping review

OBJECTIVES

When therapeutic options are limited, patients may invest hope in therapies proposed by healthcare professional, or those they find online. This review aims to explore how healthcare professional-patient communication is realised when discussing stem cell therapies.

METHOD

Four electronic databases were systematically searched for relevant studies. Twenty-six studies met the inclusion criteria. Descriptive analyses and a thematic analysis guided by a functions of medical communication framework were performed on extracted data.

RESULTS

Most included studies addressed communication in contexts of conventional stem cell therapies, such as bone marrow transplants for blood cancers. Few studies investigated communication in contexts of experimental stem cell therapies yet to receive regulatory approval. Two themes were identified as informational and relational aspects of communication, and a third theme being a mismatch in orientations.

CONCLUSIONS

Communication between healthcare professionals and patients about stem cell therapies is practised using a combination of communication approaches that do not always align with patients' needs, hopes or expectations.

PRACTICE IMPLICATIONS

The context of healthcare settings and health conditions are important when communicating about stem cell therapies. Acknowledging healthcare professionals' environmental and personal determinants can inform strategies to navigate complex discussions about stem cell therapies with patients.

Revealing the Therapeutic Potential of Stem Cells in Burn Healing: A Deeper Understanding of the Therapeutic Mechanisms of Epidermal Stem Cells and Mesenchymal Stem Cells

Background: Burns are a global public health issue and a major cause of disability and death around the world. Stem cells, which are the undifferentiated cells with the potential for indefinite proliferation and multilineage differentiation, have the ability to replace injured skin and facilitate the wound repair process through paracrine mechanisms. In light of this, the present study aims to conduct a bibliometric analysis in order to identify research hotspots of stem cell-related burns and assess global research tendencies. Methods: To achieve this objective, we retrieved scientific publications on burns associated with stem cells covering the period from January 1, 1978, to October 13, 2022, from the Web of Science Core Collection (WoSCC). Bibliometric analyses, including production and collaboration analyses between countries, institutions, authors, and journals, as well as keyword and topic analyses, were conducted using the bibliometrix R package, CiteSpace, and VOSviewer. Results: A total of 1648 burns associated with stem cell documents were published and listed on WOSCC. The most contributive country, institution, journal, and author were the United States, LV Prasad Eye Institute, Burns, and Scheffer C.G. Tseng, respectively. More importantly, combined with historical direct citation network, trend topic analysis, keyword co-occurrence network, and substantial literature analysis, we eventually summarized the research hotspots and frontiers on burns associated stem cell reasearch. Conclusion: The present study obtained deep insight into the developing trends and research hotspots on burns associated with stem cells, which arouses growing concerns and implies increasing clinical implications. The mechanism and therapeutics of epidermal stem cells (ESCs) for burn wounds and the mechanism of mesenchymal stem cells (MSCs) and MSC-derived exosomes for burns wounds are two research hotspots in this field.

A narrative review of basic and clinical studies for vocal fold regeneration therapies

OBJECTIVE

To review the various basic research and treatments available to regenerate the vocal folds and to discuss the direction for future treatments.

METHODS

A comprehensive review was performed in PubMed database and Google Scholar utilizing search terms including combinations and variations of the following concepts: vocal fold anatomy, vocal fold disorders, and regenerative therapies. No particular inclusion or exclusion criteria were set due to the nature of this narrative review article.

RESULTS/DISCUSSION

The regenerative treatments available for each vocal fold layer are the following: 1) epidermal growth factor and transforming growth factor-β1 for the epithelial layer, 2) autologous fibroblasts, autologous bone-marrow derived mesenchymal stem cells (MSCs), autologous adipose tissue-derived stromal vascular fraction (ADSVF), basic fibroblast growth factor (bFGF), collagen-hyaluronic acid nanofiber, pirfenidone, hepatocyte growth factor (HGF), pulsed dye laser (PDL), diode laser, and platelet-rich plasma (PRP) for the lamina propria, 3) bFGF and controlled-release bFGF with autologous fascia, HGF, c-Met agonistic antibody, and PRP for the muscular layer, 4) and bFGF and PRP-loaded nerve guidance conduit for the nerve. Treatments deemed clinically safe with sustained efficacy assessed up to 6 months are HGF and PDL, while bFGF, autologous fibroblasts, autologous bone marrow-derived MSCs, ADSVF, and PRP have been studied up to 12 months.

CONCLUSION

An ideal regenerative treatment is one that restores the injured or lost components of the vocal fold. The layered structure of the vocal fold allows for several mechanisms of action for these regenerative therapies. Further experimental and clinical studies are warranted, and these would dictate the impact of vocal fold regenerative therapies. Regenerative medicine may soon be at the forefront for treating vocal fold disorders. Clinicians should be open to advancements in treatment and consider the potential of novel therapies to treat specific pathologies.

Adapting to the acidic environment of the NP: RADA16-PLGA (TGF-β3) induces chondrogenic differentiation of BMSCs

Aim: RADA16-PLGA composite scaffolds constructed with simultaneous loading of BMSCs and TGF-β3 and explored their ability for chondrogenic differentiation in vitro.Methods: The performance of the composite scaffolds is assessed by rheometer assay, electron microscopic structural observation and ELISA release assay. The biosafety of the composite scaffolds is assessed by cytocompatibility assay and cell migration ability. The chondrogenic differentiation ability of composite scaffolds is evaluated by Alisin blue staining, PCR and immunofluorescence staining.Results: The composite scaffold has a good ECM-like structure, the ability to control the release of TGF-β3 and good biocompatibility. More importantly, the composite scaffolds can induce the differentiation of BMSCs to chondrocytes.Conclusion: Composite scaffolds are expected to enhance the endogenous NP repair process.

Bioengineering of Intestinal Grafts

Intestinal failure manifests as an impaired capacity of the intestine to sufficiently absorb vital nutrients and electrolytes essential for growth and well-being in pediatric and adult populations. Although parenteral nutrition remains the mainstay therapeutic approach, the pursuit of a definitive and curative strategy, such as regenerative medicine, is imperative. Substantial advancements in the field of engineered intestinal tissues present a promising avenue for addressing intestinal failure; nevertheless, extensive research is still necessary for effective translation from experimental benchwork to clinical bedside applications.

Knowledge, views and experiences of Australian optometrists in relation to ocular stem cell therapies

CLINICAL RELEVANCE

Findings from this study examining Australian optometrists' insights into ocular stem cell (SC) therapies have capacity to inform continuing professional development (CPD) about these interventions.

BACKGROUND

This study investigated Australian optometrists' knowledge, views, experiences, and preferred education sources regarding ocular SC therapies.

METHODS

An online survey was distributed to optometrists via Optometry Australia, Mivision magazine, professional groups, and social media from August 2020 to March 2021. Data were collected on demographics, and SC knowledge, awareness and experience.

RESULTS

Of 81 optometrists who completed the survey, many were metropolitan-based (85%), worked in independent practice (47%), female (56%) and >46 years of age (45%). Approximately one-fifth indicated awareness of ocular SC therapies used in standard practice; one-third had knowledge of SC clinical trials. The most noted SC therapies were for corneal disease in the United States [US] (72%) and Australia (44%). Respondents identified the availability of SC therapies for dry eye disease in Australia and the US (39% and 44% respectively), despite no regulatory-approved treatments for this indication. Clinical trials investigating inherited retinal and corneal diseases in Australia were the most commonly identified (44% and 36%, respectively). Half the respondents felt 'unsure' about the quality of evidence for treating eye conditions using SCs. One-fifth indicated concerns with these therapies; of these, most mentioned efficacy (82%), safety (76%) and/or cost (71%). About one-fifth reported being asked for advice about SCs by patients. Two-thirds felt neutral, uncomfortable, or very uncomfortable providing this advice, due to lack of knowledge or the topic being beyond their expertise. Over half (57%) were unsure if clinical management should change if patients received SC therapies. Respondents were receptive to face-to-face education.

CONCLUSION

Some optometrists responding to this survey were aware of ocular SC therapies and/or clinical trials. CPD programs may assist with maintaining currency in this evolving field.

The impact of consanguinity on the design of iPSC banks

The effect of consanguinity on identifying universal induced pluripotent stem cell (iPSC) donors, i.e., homozygous for the major human leukocyte antigen (HLA) loci, is unknown. The discovery sample size was calculated in a consanguineous population using a method (1qF) based on the inbreeding coefficient. The result was orders of magnitude smaller compared to the standard method.

The Impact of Umbilical Cord Mesenchymal Stem Cells on Motor Function in Children with Cerebral Palsy: Results of a Real-world, Compassionate use Study

The aim of this study was to analyze the impact of human umbilical cord-derived MSCs (hUC-MSCs) on motor function in children with cerebral palsy (CP). The study enrolled 152 children with CP who received up to two courses of five hUC-MSCs injections. Children's motor functions were assessed with the Gross Motor Function Measure (GMFM), 6-Minute Walk Test (6-MWT), Timed Up and Go test (Up&Go test), and Lovett's test, and mental abilities were assessed with the Clinical Global Impression (CGI) scale. Data collected at visit 1 (baseline) and visit 5 (after four injections) were analyzed retrospectively. After four hUC-MSCs administrations, all evaluated parameters improved. The change in GMFM score, by a median of 1.9 points (IQR: 0.0-8.0), correlated with age. This change was observed in all GFMCS groups and was noticed in all assessed GMFM areas. A median increase of 75 m (IQR: 20.0-115.0) was noted on the 6-MWT, and this correlated with GMFM score change. Time on the Up&Go test was reduced by a median of 2 s (IQR: -3 to - 1) and the change correlated with age, GMFM score at baseline, and the difference observed on the 6-MWT. Results of Lovett's test indicated slight changes in muscle strength. According to the CGI, 75.5% (96/151) of children were seriously (level VI) or significantly ill (level V) at the 1st visit, with any improvement observed in 63.6% (96/151) of patients at the 5th visit, 23.8% (36/151) with improvement (level II) or great improvement (level I). In conclusion, the application of hUC-MSCs generally enhanced functional performance, but individual responses varied. The therapy also benefited children with high level of disability but not to the same extent as the initially less disabled children. Although younger patients responded better to the treatment, older children can also benefit. Trial Registration 152/2018/KB/VII and 119/2021/KB/VIII. Retrospective registration in ClinicalTrials: ongoing.

Exploring the readiness of the Irish healthcare system to adopt advanced therapies: a scoping review protocol

Aim: Advanced therapy medicinal products (ATMPs) are medicines for human use that are based on genes, tissues or cells. They offer groundbreaking new opportunities for the treatment of disease and injury. However, ATMP adoption requires adjustments to current clinical practices and frameworks. This study investigates the readiness of the Irish healthcare system to adopt licensed ATMPs. Materials & methods: Scoping review, guided by the preferred reporting items for systematic reviews and meta-analyses - scoping review extension. A systematic search of English articles from 2013 to 2023 (published and grey literature) will be conducted.Results: Findings will be presented via narrative summary, graphical and tabular formats.Discussion: Review findings will be discussed in the context of recommendations that will inform national policy and strategy on the adoption of ATMPs in Ireland.

Exosomes: compositions, biogenesis, and mechanisms in diabetic wound healing

Diabetic wounds are characterized by incomplete healing and delayed healing, resulting in a considerable global health care burden. Exosomes are lipid bilayer structures secreted by nearly all cells and express characteristic conserved proteins and parent cell-associated proteins. Exosomes harbor a diverse range of biologically active macromolecules and small molecules that can act as messengers between different cells, triggering functional changes in recipient cells and thus endowing the ability to cure various diseases, including diabetic wounds. Exosomes accelerate diabetic wound healing by regulating cellular function, inhibiting oxidative stress damage, suppressing the inflammatory response, promoting vascular regeneration, accelerating epithelial regeneration, facilitating collagen remodeling, and reducing scarring. Exosomes from different tissues or cells potentially possess functions of varying levels and can promote wound healing. For example, mesenchymal stem cell-derived exosomes (MSC-exos) have favorable potential in the field of healing due to their superior stability, permeability, biocompatibility, and immunomodulatory properties. Exosomes, which are derived from skin cellular components, can modulate inflammation and promote the regeneration of key skin cells, which in turn promotes skin healing. Therefore, this review mainly emphasizes the roles and mechanisms of exosomes from different sources, represented by MSCs and skin sources, in improving diabetic wound healing. A deeper understanding of therapeutic exosomes will yield promising candidates and perspectives for diabetic wound healing management.

Insights into the role of mesenchymal stem cells in cutaneous medical aesthetics: from basics to clinics

With the development of the economy and the increasing prevalence of skin problems, cutaneous medical aesthetics are gaining more and more attention. Skin disorders like poor wound healing, aging, and pigmentation have an impact not only on appearance but also on patients with physical and psychological issues, and even impose a significant financial burden on families and society. However, due to the complexities of its occurrence, present treatment options cannot produce optimal outcomes, indicating a dire need for new and effective treatments. Mesenchymal stem cells (MSCs) and their secretomics treatment is a new regenerative medicine therapy that promotes and regulates endogenous stem cell populations and/or replenishes cell pools to achieve tissue homeostasis and regeneration. It has demonstrated remarkable advantages in several skin-related in vivo and in vitro investigations, aiding in the improvement of skin conditions and the promotion of skin aesthetics. As a result, this review gives a complete description of recent scientific breakthroughs in MSCs for skin aesthetics and the limitations of their clinical applications, aiming to provide new ideas for future research and clinical transformation.

Adipose-derived stem cell therapy for spinal cord injuries: Advances, challenges, and future directions

Spinal cord injury (SCI) has limited treatment options for regaining function. Adipose-derived stem cells (ADSCs) show promise owing to their ability to differentiate into multiple cell types, promote nerve cell survival, and modulate inflammation. This review explores ADSC therapy for SCI, focusing on its potential for improving function, preclinical and early clinical trial progress, challenges, and future directions. Preclinical studies have demonstrated ADSC transplantation's effectiveness in promoting functional recovery, reducing cavity formation, and enhancing nerve regrowth and myelin repair. To improve ADSC efficacy, strategies including genetic modification and combination with rehabilitation are being explored. Early clinical trials have shown safety and feasibility, with some suggesting motor and sensory function improvements. Challenges remain for clinical translation, including optimizing cell survival and delivery, determining dosing, addressing tumor formation risks, and establishing standardized protocols. Future research should focus on overcoming these challenges and exploring the potential for combining ADSC therapy with other treatments, including rehabilitation and medication.

Why clinical trials in disc regeneration strive to achieve completion: Insights from publication status and funding sources

Background

Chronic discogenic low back pain (LBP) poses a significant global burden, yet effective therapeutic interventions directly targeting the underlying degenerative process remain elusive. After demonstrating promising results in preclinical studies, intradiscal injection of cell-based treatments has been increasingly investigated in the clinical setting. However, most clinical trials failed to reach publication, with the few available reports showing only minor improvements. The aim of this study was to analyze the prospective clinical trials registered on ClinicalTrials.gov investigating cell therapies for LBP, with a specific emphasis on identifying critical obstacles hindering study completion, including trial design and funding sources.

Methods

A systematic search of prospective clinical trials investigating cell-based treatments for chronic LBP due to intervertebral disc degeneration was performed on ClinicalTrials.gov. Extracted data encompassed study design, recruitment, experimental treatment modalities, investigated outcomes, current status, completion date, publication status, and funding sources. Fisher's exact test assessed associations between categorical variables, while a multiple logistic regression model aimed to identify factors potentially linked to the publication status of the studies.

Results

Our search identified 26 clinical trials. Among these, only 7 (26.9%) were published, and none of the other studies marked as completed reported any results on ClinicalTrials.gov. Fifty percent of included trials were funded by universities, whereas the rest was sponsored by industry (38.5%) or private institutions (11.5%). Experimental treatments primarily involved cell-based or cell-derived products of varying sources and concentrations. Products containing carriers, such as hyaluronic acid or fibrin, were more frequently funded by industry and private organizations (p = 0.0112). No significant differences emerged when comparing published and nonpublished studies based on funding, as well as between publication status and other variables.

Conclusion

Most clinical trials exploring cell-based disc regenerative therapies for chronic LBP have never reached completion, with only a small fraction reporting preliminary data in publications.

Dual cross-linked COL1/HAp bionic gradient scaffolds containing human amniotic mesenchymal stem cells promote rotator cuff tendon-bone interface healing

The tendon-bone interface heals through scar tissue, while the lack of a natural interface gradient structure and collagen fibre alignment leads to the occurrence of retearing. Therefore, the promotion of tendon healing has become the focus of regenerative medicine. The purpose of this study was to develop a gradient COL1/ hydroxyapatite (HAp) biomaterial loaded with human amniotic mesenchymal stem cells (hAMSCs). The performance of common cross-linking agents, Genipin, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), and dual cross-linked materials were compared to select the best cross-linking mechanism to optimize the biological and mechanical properties of the scaffold. The optimal COL1/HAp-loaded with hAMSCs were implanted into the tendon-bone rotator cuff interfaces in rats and the effect on the tendon-bone healing was assessed by micro-CT, histological analysis, and biomechanical properties. The results showed that Genipin and EDC/NHS dual cross-linked COL1/HAp had good biological activity and mechanical properties and promoted the proliferation and differentiation of hAMSCs. Animal experiments showed that the group using a scaffold loaded with hAMSCs had excellent continuity and orientation of collagen fibers, increased fibrocartilage and bone formation, and significantly higher biomechanical functions than the control group at the interface at 12 weeks post operation. This study demonstrated that dual cross-linked gradient COL1/HAp-loaded hAMSCs could promote interface healing, thereby providing a feasible strategy for tendon-bone interface regeneration.

Standardisation is the key to the sustained, rapid and healthy development of stem cell-based therapy

BACKGROUND

Stem cell-based therapy (SCT) is an important component of regenerative therapy that brings hope to many patients. After decades of development, SCT has made significant progress in the research of various diseases, and the market size has also expanded significantly. The transition of SCT from small-scale, customized experiments to routine clinical practice requires the assistance of standards. Many countries and international organizations around the world have developed corresponding SCT standards, which have effectively promoted the further development of the SCT industry.

METHODS

We conducted a comprehensive literature review to introduce the clinical application progress of SCT and focus on the development status of SCT standardization.

RESULTS

We first briefly introduced the types and characteristics of stem cells, and summarized the current clinical application and market development of SCT. Subsequently, we focused on the development status of SCT-related standards as of now from three levels: the International Organization for Standardization (ISO), important international organizations, and national organizations. Finally, we provided perspectives and conclusions on the significance and challenges of SCT standardization.

CONCLUSIONS

Standardization plays an important role in the sustained, rapid and healthy development of SCT.

Cell-mediated exon skipping normalizes dystrophin expression and muscle function in a new mouse model of Duchenne Muscular Dystrophy

Cell therapy for muscular dystrophy has met with limited success, mainly due to the poor engraftment of donor cells, especially in fibrotic muscle at an advanced stage of the disease. We developed a cell-mediated exon skipping that exploits the multinucleated nature of myofibers to achieve cross-correction of resident, dystrophic nuclei by the U7 small nuclear RNA engineered to skip exon 51 of the dystrophin gene. We observed that co-culture of genetically corrected human DMD myogenic cells (but not of WT cells) with their dystrophic counterparts at a ratio of either 1:10 or 1:30 leads to dystrophin production at a level several folds higher than what predicted by simple dilution. This is due to diffusion of U7 snRNA to neighbouring dystrophic resident nuclei. When transplanted into NSG-mdx-Δ51mice carrying a mutation of exon 51, genetically corrected human myogenic cells produce dystrophin at much higher level than WT cells, well in the therapeutic range, and lead to force recovery even with an engraftment of only 3-5%. This level of dystrophin production is an important step towards clinical efficacy for cell therapy.

A perioperative layered autologous tissue expansion graft for hollow organ repair

Tissue engineering has not been widely adopted in clinical settings for several reasons, including technical challenges, high costs, and regulatory complexity. Here, we introduce the Perioperative Layered Autologous Tissue Expansion graft (PLATE graft), a composite biomaterial and collagen-reinforced construct with autologous epithelium on one side and smooth muscle tissue on the other. Designed to mimic the structure and function of natural hollow organs, the PLATE graft is unique in that it can be produced in a standard operating theatre and is cost-effective. In this proof-of-principle study, we test its regenerative performance in eight different organs, present biomechanical and permeability tests, and finally explore its in vivo performance in live rabbits.

Clinical trial designs and endpoints

Trials should be designed with consideration of the individual disease context and research question. Many different approaches may be justified. In this chapter, we therefore consider some of the principal components of trial design in general and within the context of the emerging field of gene and cell therapies. Many aspects of developing a trial protocol require striking a balance between scientific rigor and practicalities for which the voice of patients and their families should form an integral part. We outline the importance of the acceptability of trial designs to participants, the determination of a target population and eligibility criteria, stratification methods that ensure a balanced control of variance across the trial, adequate controls to answer research questions including considerations of placebo allocation, blinding, and endpoints.

Ultrasound-Responsive Micelle-Encapsulated Mesenchymal Stem Cell-Derived EVs for the Treatment of Lower Limb Microcirculation Disease

Lower limb microcirculatory ischemic disease is a vascular disorder primarily characterized by limb pain, gangrene, and potential amputation. It can be caused by various factors, such as hyperglycemia, atherosclerosis, and infection. Due to the extremely narrow luminal diameter in lower limb microcirculatory ischemic lesions, both surgical and medical interventions face challenges in achieving satisfactory therapeutic outcomes within the microvessels. Extracellular vesicles derived from mesenchymal stem cells (MSCs-EVs) exhibit promising potential in the treatment of microcirculation ischemic lesions due to their small size and ability to promote angiogenesis. After undergoing substantial losses during the process of EVs transportation, only a minimal fraction of EVs can effectively reach the site of microcirculatory lesions, thereby compromising the therapeutic efficacy for microcirculatory disorders. Herein, an ultrasound-responsive system utilizing 2-(dimethylamino)ethyl methacrylate-b-2-tetrahydropyranyl methacrylate (DMAEMA-b-THPMA) micelles to encapsulate MSCs-EVs has been successfully constructed, with the aim of achieving localized and targeted release of EVs at the site of microcirculatory lesions. The reversible addition-fragmentation chain transfer (RAFT) polymerization method facilitates the successful synthesis of diblock copolymers comprising monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA) and monomer 2-tetrahydropyranyl methacrylate (THPMA). The DMAEMA-b-THPMA micelles exhibit a nanoscale structure, reliable biocompatibility, ultrasound responsiveness, and conspicuous protection of EVs. Furthermore, the implementation of low-energy-density ultrasound can enhance angiogenesis by upregulating the levels of the vascular endothelial growth factor (VEGF). In in vivo experiments, the ultrasound-responsive system of the DMAEMA-b-THPMA micelles and MSCs-EVs synergistically enhances therapeutic efficacy by promoting angiogenesis, improving vascular permeability, and optimizing vascular. In conclusion, this work demonstrates bioapplication of an ultrasound-responsive micellar nanosystem loaded with EVs for the treatment of lower limb microcirculatory ischemic disorders.

Management of partial-thickness rotator cuff tears with autologous adipose-derived regenerative cells is safe and more effective than injection of corticosteroid

Symptomatic, partial-thickness rotator cuff tears (sPTRCT) are problematic. This study tested the hypothesis that management of sPTRCT with injection of fresh, uncultured, unmodified, autologous, adipose-derived regenerative cells (UA-ADRCs) is safe and more effective than injection of corticosteroid even in the long run. To this end, subjects who had completed a former randomized controlled trial were enrolled in the present study. At baseline these subjects had not responded to physical therapy treatments for at least 6 weeks, and were randomly assigned to receive respectively a single injection of UA-ADRCs (n = 11) or a single injection of methylprednisolone (n = 5). Efficacy was assessed using the ASES Total score, pain visual analogue scale (VAS), RAND Short Form-36 Health Survey and range of motion at 33.2 ± 1.0 (mean ± SD) and 40.6 ± 1.9 months post-treatment. Proton density, fat-saturated, T2-weighted MRI of the index shoulder was performed at both study visits. There were no greater risks connected with injection of UA-ADRCs than those connected with injection of corticosteroid. The subjects in the UA-ADRCs group showed statistically significantly higher mean ASES Total scores than the subjects in the corticosteroid group. The MRI scans at 6 months post-treatment allowed to "watch the UA-ADRCs at work".

Development and qualification of clinical grade decellularized and cryopreserved human esophagi

Tissue engineering is a promising alternative to current full thickness circumferential esophageal replacement methods. The aim of our study was to develop a clinical grade Decellularized Human Esophagus (DHE) for future clinical applications. After decontamination, human esophagi from deceased donors were placed in a bioreactor and decellularized with sodium dodecyl sulfate (SDS) and ethylendiaminetetraacetic acid (EDTA) for 3 days. The esophagi were then rinsed in sterile water and SDS was eliminated by filtration on an activated charcoal cartridge for 3 days. DNA was removed by a 3-hour incubation with DNase. A cryopreservation protocol was evaluated at the end of the process to create a DHE cryobank. The decellularization was efficient as no cells and nuclei were observed in the DHE. Sterility of the esophagi was obtained at the end of the process. The general structure of the DHE was preserved according to immunohistochemical and scanning electron microscopy images. SDS was efficiently removed, confirmed by a colorimetric dosage, lack of cytotoxicity on Balb/3T3 cells and mesenchymal stromal cell long term culture. Furthermore, DHE did not induce lymphocyte proliferation in-vitro. The cryopreservation protocol was safe and did not affect the tissue, preserving the biomechanical properties of the DHE. Our decellularization protocol allowed to develop the first clinical grade human decellularized and cryopreserved esophagus.

How Smart are Smart Materials? A Conceptual and Ethical Analysis of Smart Lifelike Materials for the Design of Regenerative Valve Implants

It may soon become possible not just to replace, but to re-grow healthy tissues after injury or disease, because of innovations in the field of Regenerative Medicine. One particularly promising innovation is a regenerative valve implant to treat people with heart valve disease. These implants are fabricated from so-called 'smart', 'lifelike' materials. Implanted inside a heart, these implants stimulate re-growth of a healthy, living heart valve. While the technological development advances, the ethical implications of this new technology are still unclear and a clear conceptual understanding of the notions 'smart' and 'lifelike' is currently lacking. In this paper, we explore the conceptual and ethical implications of the development of smart lifelike materials for the design of regenerative implants, by analysing heart valve implants as a showcase. In our conceptual analysis, we show that the materials are considered 'smart' because they can communicate with human tissues, and 'lifelike' because they are structurally similar to these tissues. This shows that regenerative valve implants become intimately integrated in the living tissues of the human body. As such, they manifest the ontological entanglement of body and technology. In our ethical analysis, we argue this is ethically significant in at least two ways: It exacerbates the irreversibility of the implantation procedure, and it might affect the embodied experience of the implant recipient. With our conceptual and ethical analysis, we aim to contribute to responsible development of smart lifelike materials and regenerative implants.

Kidney Bioengineering for Transplantation

The kidney is an important organ for maintenance of homeostasis in the human body. As renal failure progresses, renal replacement therapy becomes necessary. However, there is a chronic shortage of kidney donors, creating a major problem for transplantation. To solve this problem, many strategies for the generation of transplantable kidneys are under investigation. Since the first reports describing that nephron progenitors could be induced from human induced pluripotent stem cells, kidney organoids have been attracting attention as tools for studying human kidney development and diseases. Because the kidney is formed through the interactions of multiple renal progenitors, current studies are investigating ways to combine these progenitors derived from human induced pluripotent stem cells for the generation of transplantable kidney organoids. Other bioengineering strategies, such as decellularization and recellularization of scaffolds, 3-dimensional bioprinting, interspecies blastocyst complementation and progenitor replacement, and xenotransplantation, also have the potential to generate whole kidneys, although each of these strategies has its own challenges. Combinations of these approaches will lead to the generation of bioengineered kidneys that are transplantable into humans.

A new era of macrophage-based cell therapy

Macrophages are essential innate immune cells found throughout the body that have protective and pathogenic functions in many diseases. When activated, macrophages can mediate the phagocytosis of dangerous cells or materials and participate in effective tissue regeneration by providing growth factors and anti-inflammatory molecules. Ex vivo-generated macrophages have thus been used in clinical trials as cell-based therapies, and based on their intrinsic characteristics, they outperformed stem cells within specific target diseases. In addition to the old methods of generating naïve or M2 primed macrophages, the recently developed chimeric antigen receptor-macrophages revealed the potential of genetically engineered macrophages for cell therapy. Here, we review the current developmental status of macrophage-based cell therapy. The findings of important clinical and preclinical trials are updated, and patent status is investigated. Additionally, we discuss the limitations and future directions of macrophage-based cell therapy, which will help broaden the potential utility and clinical applications of macrophages.

MesenchymAl stromal cells for Traumatic bRain Injury (MATRIx): a study protocol for a multicenter, double-blind, randomised, placebo-controlled phase II trial

BACKGROUND

Traumatic brain injury (TBI) is a significant cause of death and disability, with no effective neuroprotective drugs currently available for its treatment. Mesenchymal stromal cell (MSC)-based therapy shows promise as MSCs release various soluble factors that can enhance the injury microenvironment through processes, such as immunomodulation, neuroprotection, and brain repair. Preclinical studies across different TBI models and severities have demonstrated that MSCs can improve functional and structural outcomes. Moreover, clinical evidence supports the safety of third-party donor bank-stored MSCs in adult subjects. Building on this preclinical and clinical data, we present the protocol for an academic, investigator-initiated, multicenter, double-blind, randomised, placebo-controlled, adaptive phase II dose-finding study aiming to evaluate the safety and efficacy of intravenous administration of allogeneic bone marrow-derived MSCs to severe TBI patients within 48 h of injury.

METHODS/DESIGN

The study will be conducted in two steps. Step 1 will enrol 42 patients, randomised in a 1:1:1 ratio to receive 80 million MSCs, 160 million MSCs or a placebo to establish safety and identify the most promising dose. Step 2 will enrol an additional 36 patients, randomised in a 1:1 ratio to receive the selected dose of MSCs or placebo. The activity of MSCs will be assessed by quantifying the plasmatic levels of neurofilament light (NfL) at 14 days as a biomarker of neuronal damage. It could be a significant breakthrough if the study demonstrates the safety and efficacy of MSC-based therapy for severe TBI patients. The results of this trial could inform the design of a phase III clinical trial aimed at establishing the efficacy of the first neurorestorative therapy for TBI.

DISCUSSION

Overall, the MATRIx trial is a critical step towards developing an effective treatment for TBI, which could significantly improve the lives of millions worldwide affected by this debilitating condition. Trial Registration EudraCT: 2022-000680-49.

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.

Integrative Analysis Reveals the Diverse Effects of 3D Stiffness upon Stem Cell Fate

The origin of life and native tissue development are dependent on the heterogeneity of pluripotent stem cells. Bone marrow mesenchymal stem cells (BMMSCs) are located in a complicated niche with variable matrix stiffnesses, resulting in divergent stem cell fates. However, how stiffness drives stem cell fate remains unknown. For this study, we performed whole-gene transcriptomics and precise untargeted metabolomics sequencing to elucidate the complex interaction network of stem cell transcriptional and metabolic signals in extracellular matrices (ECMs) with different stiffnesses, and we propose a potential mechanism involved in stem cell fate decision. In a stiff (39~45 kPa) ECM, biosynthesis of aminoacyl-tRNA was up-regulated, and increased osteogenesis was also observed. In a soft (7~10 kPa) ECM, biosynthesis of unsaturated fatty acids and deposition of glycosaminoglycans were increased, accompanied by enhanced adipogenic/chondrogenic differentiation of BMMSCs. In addition, a panel of genes responding to the stiffness of the ECM were validated in vitro, mapping out the key signaling network that regulates stem cells' fate decisions. This finding of "stiffness-dependent manipulation of stem cell fate" provides a novel molecular biological basis for development of potential therapeutic targets within tissue engineering, from both a cellular metabolic and a biomechanical perspective.

Revolutionizing Radiotoxicity Management with Mesenchymal Stem Cells and Their Derivatives: A Focus on Radiation-Induced Cystitis

Although radiation therapy plays a crucial role in cancer treatment, and techniques have improved continuously, irradiation induces side effects in healthy tissue. Radiation cystitis is a potential complication following the therapeutic irradiation of pelvic cancers and negatively impacts patients' quality of life (QoL). To date, no effective treatment is available, and this toxicity remains a therapeutic challenge. In recent times, stem cell-based therapy, particularly the use of mesenchymal stem cells (MSC), has gained attention in tissue repair and regeneration due to their easy accessibility and their ability to differentiate into several tissue types, modulate the immune system and secrete substances that help nearby cells grow and heal. In this review, we will summarize the pathophysiological mechanisms of radiation-induced injury to normal tissues, including radiation cystitis (RC). We will then discuss the therapeutic potential and limitations of MSCs and their derivatives, including packaged conditioned media and extracellular vesicles, in the management of radiotoxicity and RC.

The Ethical Implications of Tissue Engineering for Regenerative Purposes: A Systematic Review

Tissue Engineering (TE) is a branch of Regenerative Medicine (RM) that combines stem cells and biomaterial scaffolds to create living tissue constructs to restore patients' organs after injury or disease. Over the last decade, emerging technologies such as 3D bioprinting, biofabrication, supramolecular materials, induced pluripotent stem cells, and organoids have entered the field. While this rapidly evolving field is expected to have great therapeutic potential, its development from bench to bedside presents several ethical and societal challenges. To make sure TE will reach its ultimate goal of improving patient welfare, these challenges should be mapped out and evaluated. Therefore, we performed a systematic review of the ethical implications of the development and application of TE for regenerative purposes, as mentioned in the academic literature. A search query in PubMed, Embase, Scopus, and PhilPapers yielded 2451 unique articles. After systematic screening, 237 relevant ethical and biomedical articles published between 2008 and 2021 were included in our review. We identified a broad range of ethical implications that could be categorized under 10 themes. Seven themes trace the development from bench to bedside: (1) animal experimentation, (2) handling human tissue, (3) informed consent, (4) therapeutic potential, (5) risk and safety, (6) clinical translation, and (7) societal impact. Three themes represent ethical safeguards relevant to all developmental phases: (8) scientific integrity, (9) regulation, and (10) patient and public involvement. This review reveals that since 2008 a significant body of literature has emerged on how to design clinical trials for TE in a responsible manner. However, several topics remain in need of more attention. These include the acceptability of alternative translational pathways outside clinical trials, soft impacts on society and questions of ownership over engineered tissues. Overall, this overview of the ethical and societal implications of the field will help promote responsible development of new interventions in TE and RM. It can also serve as a valuable resource and educational tool for scientists, engineers, and clinicians in the field by providing an overview of the ethical considerations relevant to their work. Impact statement To our knowledge, this is the first time that the ethical implications of Tissue Engineering (TE) have been reviewed systematically. By gathering existing scholarly work and identifying knowledge gaps, this review facilitates further research into the ethical and societal implications of TE and Regenerative Medicine (RM) and other emerging biomedical technologies. Moreover, it will serve as a valuable resource and educational tool for scientists, engineers, and clinicians in the field by providing an overview of the ethical considerations relevant to their work. As such, our review may promote successful and responsible development of new strategies in TE and RM.

Remote control of the recruitment and capture of endogenous stem cells by ultrasound for in situ repair of bone defects

Stem cell-based tissue engineering has provided a promising platform for repairing of bone defects. However, the use of exogenous bone marrow mesenchymal stem cells (BMSCs) still faces many challenges such as limited sources and potential risks. It is important to develop new approach to effectively recruit endogenous BMSCs and capture them for in situ bone regeneration. Here, we designed an acoustically responsive scaffold (ARS) and embedded it into SDF-1/BMP-2 loaded hydrogel to obtain biomimetic hydrogel scaffold complexes (BSC). The SDF-1/BMP-2 cytokines can be released on demand from the BSC implanted into the defected bone via pulsed ultrasound (p-US) irradiation at optimized acoustic parameters, recruiting the endogenous BMSCs to the bone defected or BSC site. Accompanied by the daily p-US irradiation for 14 days, the alginate hydrogel was degraded, resulting in the exposure of ARS to these recruited host stem cells. Then another set of sinusoidal continuous wave ultrasound (s-US) irradiation was applied to excite the ARS intrinsic resonance, forming highly localized acoustic field around its surface and generating enhanced acoustic trapping force, by which these recruited endogenous stem cells would be captured on the scaffold, greatly promoting them to adhesively grow for in situ bone tissue regeneration. Our study provides a novel and effective strategy for in situ bone defect repairing through acoustically manipulating endogenous BMSCs.

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We designed ARS and embedded it into SDF-1/BMP-2 loaded hydrogel to form BSC.

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The BSC can release SDF-1/BMP-2 by p-US irradiation for recruitment of endogenous BMSCs and capture them by s-US irradiation.

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The in situ repair of bone defects were successfully realized by US-mediated control of the recruitment and capture of BMSCs.

Cell-based therapies have disease-modifying effects on osteoarthritis in animal models. A systematic review by the ESSKA Orthobiologic Initiative. Part 2: bone marrow-derived cell-based injectable therapies

PURPOSE

Aim of this systematic review was to determine if bone marrow-derived cell-based injectable therapies induce disease-modifying effects in joints affected by osteoarthritis (OA) in animal models.

METHODS

A systematic review was performed on three electronic databases (PubMed, Web of Science, Embase) according to PRISMA guidelines. A synthesis of the results was performed investigating disease-modifying effects in preclinical animal studies comparing injectable bone marrow-derived products with OA controls or other products, different formulations or injection intervals, and the combination with other products. The risk of bias was assessed according to the SYRCLE's tool.

RESULTS

Fifty-three studies were included (1819 animals) with an increasing publication trend over time. Expanded cells were used in 48 studies, point-of-care products in 3 studies, and both approaches were investigated in 2 studies. Among the 47 studies presenting results on the disease-modifying effects, 40 studies (85%) reported better results with bone marrow-derived products compared to OA controls, with positive findings evident in 14 out of 20 studies (70%) in macroscopic assessment, in 30 out of 41 studies (73%) in histological assessment, and in 10 out of 13 studies (77%) in immunohistochemical evaluations. Clinical evaluations showed positive results in 7 studies out of 9 (78%), positive imaging results in 11 studies out of 17 (65%), and positive biomarker results in 5 studies out of 10 (50%). While 36 out of 46 studies (78%) reported positive results at the cartilage level, only 3 out of 10 studies (30%) could detect positive changes at the synovial level. The risk of bias was low in 42% of items, unclear in 50%, and high in 8%.

CONCLUSION

This systematic review of preclinical studies demonstrated that intra-articular injections of bone marrow-derived products can induce disease-modifying effects in the treatment of OA, slowing down the progression of cartilage damage with benefits at macroscopic, histological, and immunohistochemical levels. Positive results have been also observed in terms of clinical and imaging findings, as well as in the modulation of inflammatory and cartilage biomarkers, while poor effects have been described on the synovial membrane. These findings are important to understand the potential of bone marrow-derived products and to guide further research to optimise their use in the clinical practice.

LEVEL OF EVIDENCE

II.

A review focusing on the benefits of plant-derived polysaccharides for osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by progressive cartilage degeneration, which imposes a heavy physical and financial burden on the middle-aged and elderly population. As the pathogenesis of OA has not been fully elucidated, it is of great importance to develop targeted therapeutic or preventive medications. Traditional therapeutic drugs, such as non-steroidal anti-inflammatory drugs, steroids and opioids, have significant side effects, making the exploration for safe and effective alternative therapeutic drugs urgent. In recent years, many studies have reported the role of plant-derived polysaccharides in anti-inflammation, anti-oxidation, regulation of chondrocyte metabolism and proliferation, and cartilage protection, and have demonstrated their great potential in the treatment of OA. Therefore, by focusing on studies related to the intervention of plant-derived polysaccharides in OA, including in vivo and in vitro experiments, this review aimed to classify and summarize the existing research findings according to different mechanisms of action. In addition, reports on plant-derived polysaccharides as nanoparticles were also explored. Then, candidate monomers and theoretical bases were provided for the further development and application of novel drugs in the treatment of OA.

Cell membrane-targeting NIR fluorescent probes with large Stokes shifts for ultralong-term transplanted neural stem cell tracking

There is an emerging therapeutic strategy to transplant stem cells into diseased host tissue for various neurodegenerative diseases, owing to their self-renewal ability and pluripotency. However, the traceability of long-term transplanted cells limits the further understanding of the mechanism of the therapy. Herein, we designed and synthesized a quinoxalinone scaffold-based near-infrared (NIR) fluorescent probe named QSN, which exhibits ultra-strong photostability, large Stokes shift, and cell membrane-targeting capacity. It could be found that QSN-labeled human embryonic stem cells showed strong fluorescent emission and photostability both in vitro and in vivo. Additionally, QSN would not impair the pluripotency of embryonic stem cells, indicating that QSN did not perform cytotoxicity. Moreover, it is worth mentioning that QSN-labeled human neural stem cells held cellular retention for at least 6 weeks in the mouse brain striatum post transplantation. All these findings highlight the potential application of QSN for ultralong-term transplanted cell tracking.

Cost and availability of novel cell and gene therapies: Can we avoid a catastrophic second valley of death?: Can we avoid a catastrophic second valley of death?

Advanced gene and cellular therapies risk a second "valley of death" due to their high costs and low patient population. As these are life-saving therapies, measures are urgently needed to prevent their withdrawal from the market.

Polymeric Materials, Advances and Applications in Tissue Engineering: A Review

Tissue Engineering (TE) is an interdisciplinary field that encompasses materials science in combination with biological and engineering sciences. In recent years, an increase in the demand for therapeutic strategies for improving quality of life has necessitated innovative approaches to designing intelligent biomaterials aimed at the regeneration of tissues and organs. Polymeric porous scaffolds play a critical role in TE strategies for providing a favorable environment for tissue restoration and establishing the interaction of the biomaterial with cells and inducing substances. This article reviewed the various polymeric scaffold materials and their production techniques, as well as the basic elements and principles of TE. Several interesting strategies in eight main TE application areas of epithelial, bone, uterine, vascular, nerve, cartilaginous, cardiac, and urinary tissue were included with the aim of learning about current approaches in TE. Different polymer-based medical devices approved for use in clinical trials and a wide variety of polymeric biomaterials are currently available as commercial products. However, there still are obstacles that limit the clinical translation of TE implants for use wide in humans, and much research work is still needed in the field of regenerative medicine.

Engineered tissue vascularization and engraftment depends on host model

Developing vascular networks that integrate with the host circulation and support cells engrafted within engineered tissues remains a key challenge in tissue engineering. Most previous work in this field has focused on developing new methods to build human vascular networks within engineered tissues prior to their implant in vivo, with substantively less attention paid to the role of the host in tissue vascularization and engraftment. Here, we assessed the role that different host animal models and anatomic implant locations play in vascularization and cardiomyocyte survival within engineered tissues. We found major differences in the formation of graft-derived blood vessels and survival of cardiomyocytes after implantation of identical tissues in immunodeficient athymic nude mice versus rats. Athymic mice supported robust guided vascularization of human microvessels carrying host blood but relatively sparse cardiac grafts within engineered tissues, regardless of implant site. Conversely, athymic rats produced substantive inflammatory changes that degraded grafts (abdomen) or disrupted vascular patterning (heart). Despite disrupted vascular patterning, athymic rats supported > 3-fold larger human cardiomyocyte grafts compared to athymic mice. This work demonstrates the critical importance of the host for vascularization and engraftment of engineered tissues, which has broad translational implications across regenerative medicine.

Microneedle system for tissue engineering and regenerative medicine

Global increasing demand for high life quality and length facilitates the development of tissue engineering and regenerative medicine, which apply multidisciplinary theories and techniques to achieve the structural reconstruction and functional recovery of disordered or damaged tissues and organs. However, the clinical performances of adopted drugs, materials, and powerful cells in the laboratory are inescapably limited by the currently available technologies. To tackle the problems, versatile microneedles are developed as the new platform for local delivery of diverse cargos with minimal invasion. The efficient delivery, as well as painless and convenient procedure endow microneedles with good patient compliance in clinic. In this review, we first categorize different microneedle systems and delivery models, and then summarize their applications in tissue engineering and regenerative medicine mainly involving maintenance and rehabilitation of damaged tissues and organs. In the end, we discuss the advantages, challenges, and prospects of microneedles in depth for future clinical translations.

Engineered hydrogels for mechanobiology

Cells' local mechanical environment can be as important in guiding cellular responses as many well-characterized biochemical cues. Hydrogels that mimic the native extracellular matrix can provide these mechanical cues to encapsulated cells, allowing for the study of their impact on cellular behaviours. Moreover, by harnessing cellular responses to mechanical cues, hydrogels can be used to create tissues in vitro for regenerative medicine applications and for disease modelling. This Primer outlines the importance and challenges of creating hydrogels that mimic the mechanical and biological properties of the native extracellular matrix. The design of hydrogels for mechanobiology studies is discussed, including appropriate choice of cross-linking chemistry and strategies to tailor hydrogel mechanical cues. Techniques for characterizing hydrogels are explained, highlighting methods used to analyze cell behaviour. Example applications for studying fundamental mechanobiological processes and regenerative therapies are provided, along with a discussion of the limitations of hydrogels as mimetics of the native extracellular matrix. The article ends with an outlook for the field, focusing on emerging technologies that will enable new insights into mechanobiology and its role in tissue homeostasis and disease.

The PCK2-glycolysis axis assists three-dimensional-stiffness maintaining stem cell osteogenesis

Understanding mechanisms underlying the heterogeneity of multipotent stem cells offers invaluable insights into biogenesis and tissue development. Extracellular matrix (ECM) stiffness has been acknowledged as a crucial factor regulating stem cell fate. However, how cells sense stiffness cues and adapt their metabolism activity is still unknown. Here we report the novel role of mitochondrial phosphoenolpyruvate carboxykinase (PCK2) in enhancing osteogenesis in 3D ECM via glycolysis. We experimentally mimicked the physical characteristics of 3D trabeculae network of normal and osteoporotic bone with different microstructure and stiffness, observing that PCK2 promotes osteogenesis in 3D ECM with tunable stiffness in vitro and in vivo. Mechanistically, PCK2 enhances the rate-limiting metabolic enzyme pallet isoform phosphofructokinase (PFKP) in 3D ECM, and further activates AKT/extracellular signal-regulated kinase 1/2 (ERK1/2) cascades, which directly regulates osteogenic differentiation of MSCs. Collectively, our findings implicate an intricate crosstalk between cell mechanics and metabolism, and provide new perspectives for strategies of osteoporosis.

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As the key rate-limiting enzyme of gluconeogenesis, PCK2 manipulates osteogenesis in stiff and soft ECM in vitro and in vivo.

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PCK2 regulates osteogenic capacity of BMMSCs in 3D ECM with different stiffness, via modulating glycolysis and regulating PFKP-AKT/ERK signaling pathways.

Airway replacement using stented aortic matrices: Long-term follow-up and results of the TRITON-01 study in 35 adult patients

Over the past 25 years, we have demonstrated the feasibility of airway bioengineering using stented aortic matrices experimentally then in a first-in-human trial (n = 13). The present TRITON-01 study analyzed all the patients who had airway replacement at our center to confirm that this innovative approach can be now used as usual care. For each patient, the following data were prospectively collected: postoperative mortality and morbidity, late airway complications, stent removal and status at last follow-up on November 2, 2021. From October 2009 to October 2021, 35 patients had airway replacement for malignant (n = 29) or benign (n = 6) lesions. The 30-day postoperative mortality and morbidity rates were 2.9% (n = 1/35) and 22.9% (n = 8/35) respectively. At a median follow-up of 29.5 months (range 1-133 months), 27 patients were alive. There have been no deaths directly related to the implanted bioprosthesis. Eighteen patients (52.9%) had stent-related granulomas requiring a bronchoscopic treatment. Ten among 35 patients (28.6%) achieved a stent free survival. The actuarial 2- and 5-year survival rates (Kaplan-Meier estimates) were respectively 88% and 75%. The TRITON-01 study confirmed that airway replacement using stented aortic matrices can be proposed as usual care at our center. Clinicaltrials.gov Identifier: NCT04263129.