Matrix reverses immortalization-mediated stem cell fate determination

Distinct role of perlecan in mesenchymal tissue regeneration via genetic and epigenetic modification

Perlecan (HSPG2), a key component of basement membrane proteins, plays a crucial role in tissue development and regeneration. However, its direct impact on mesenchymal tissue differentiation, mediated through both genetic modification (gain- and loss-of-function mutations) and epigenetic changes (matrix microenvironment alterations), remains underexplored. In this study, we utilized CRISPR/Cas9 to achieve knockout (KO) and overexpression (OE) of HSPG2 in human fetal nucleus pulposus stem/progenitor cells (NPSCs) and adult infrapatellar fat pad-derived stem cells (IPFSCs) to investigate perlecan's influence on mesenchymal differentiation. We also assessed the effects of decellularized extracellular matrix (dECM) derived from fetal NPSCs with modified HSPG2 expression on the proliferation and differentiation of adult NPSCs. Our findings demonstrate that HSPG2-KO enhance chondrogenic differentiation, while HSPG2-OE suppressed adipogenic differentiation in both fetal NPSCs and adult IPFSCs. Notably, dECM from HSPG2-OE fetal NPSCs significantly promoted chondrogenic differentiation in adult NPSCs, suggesting potential applications for perlecan in developing advanced biomaterials for cartilage regeneration.

The influence of interleukin-27 on metabolic fitness in a murine neonatal model of bacterial sepsis

Human neonates are predisposed to an increased risk of mortality from infection due to fundamental differences in the framework of innate and adaptive immune responses relative to those in the adult population. As one key difference in neonates, an increase in the immunosuppressive cytokine, IL-27, is responsible for poor outcomes in a murine neonatal model of bacterial sepsis. In our model, the absence of IL-27 signaling during infection is associated with improved maintenance of body mass, increased bacterial clearance with reduced systemic inflammation, and decreased mortality rates that correlate to preservation of glucose homeostasis and insulin production. To further elucidate the mechanisms associated with IL-27 signaling and metabolic fitness, we analyzed global transcriptomes from spleen, liver, pancreas, and hindlimb muscle during Escherichia coli-induced sepsis in wild-type (WT) and IL-27Rα-deficient (KO) mice. Metabolically important tissues such as the liver, pancreas, and hindlimb muscle exhibit a shift in differential gene expression of pathways involved in oxidative phosphorylation, glycolysis, gluconeogenesis, lipid metabolism, and fatty acid β oxidation. The hindlimb muscle of KO pups demonstrated a significant reduction in all of these pathways during infection. The KO liver showed a significant down-regulation in gluconeogenesis and glycolytic pathways. Collectively, these findings suggest a negative influence of IL-27 on the metabolic profile during early-life infection. This is an important consideration for antagonization of IL-27 as a potential host-directed therapeutic opportunity as our findings point to an overall improvement in infectious disease parameters and metabolic fitness.NEW & NOTEWORTHY IL-27 has been linked with immune regulation during infection, but this is the first report of a combined influence of IL-27 on complete host response during systemic infection with metabolic fitness in a neonate. Novel findings demonstrate improved glucose homeostasis and insulin response supported by a reduced expression of genes involved in gluconeogenesis in the absence of IL-27 signaling. An increased expression of genes integral to cholesterol biosynthesis further supports a protective response during sepsis.

Charting a quarter-century of commercial cartilage regeneration products

Functional cartilage regeneration remains difficult to achieve despite decades of research. Dozens of commercial products have been proposed, with each targeting different facets of successful cartilage engineering, including mechanical properties, integration, lubrication and inflammation; however, there remains a lack of breakthroughs in meaningful clinical outcomes. Prior research categorized commercial products based on their components and elucidated challenges faced during the market approval process. This paper, for the first time, comprehensively reviews the properties of commercial products covering the last 25 years, including design trends in components, compatibility with minimally invasive surgery, indications for cartilage defects, long-term follow-up, as well as active sponsorship support of the International Cartilage Regeneration and Joint Preservation Society (ICRS). We aim to summarize the key factors for potentially successful commercial products and elucidate overarching trends in technology development in this field. Given that no revolutionary products have yielded significantly improved clinical results, emerging products compete with one another on user-friendliness and cost-efficiency. Other relevant characteristics include compatibility with minimally invasive surgery, extensiveness of required surgery (one-stage vs. two-stage), use of versatile artificial polymers and application of cells and biomaterials. Specific products continue to lead the market due to their cost-efficiency or indications for larger cartilage defects. However, they have been shown to result in no significant improvement upon clinical follow-up. Thus, there is a need for products that surpass current commercial products and show clinical effectiveness. Translation potential of this article: This review analyzes product components, compatibility with minimally invasive surgery, indication for cartilage defect areas, clinical performance as well as sponsorship for the World Conference of International Cartilage Regeneration & Joint Preservation Society, based on information about cartilage regeneration products from 1997 to 2023. It shines a light on future development of design and commercialization of cartilage products.

Navigating stem cell culture: insights, techniques, challenges, and prospects

Stem cell research holds huge promise for regenerative medicine and disease modeling, making the understanding and optimization of stem cell culture a critical aspect of advancing these therapeutic applications. This comprehensive review provides an in-depth overview of stem cell culture, including general information, contemporary techniques, encountered problems, and future perspectives. The article begins by explaining the fundamental characteristics of various stem cell types, elucidating the importance of proper culture conditions in maintaining pluripotency or lineage commitment. A detailed exploration of established culture techniques sheds light on the evolving landscape of stem cell culture methodologies. Common challenges such as genetic stability, heterogeneity, and differentiation efficiency are thoroughly discussed, with insights into cutting-edge strategies and technologies aimed at addressing these hurdles. Moreover, the article delves into the impact of substrate materials, culture media components, and biophysical cues on stem cell behavior, emphasizing the intricate interplay between the microenvironment and cell fate decisions. As stem cell research advances, ethical considerations and regulatory frameworks become increasingly important, prompting a critical examination of these aspects in the context of culture practices. Lastly, the article explores emerging perspectives, including the integration of artificial intelligence and machine learning in optimizing culture conditions, and the potential applications of stem cell-derived products in personalized medicine. This comprehensive overview aims to serve as a valuable resource for researchers and clinicians, fostering a deeper understanding of stem cell culture and its key role in advancing regenerative medicine and biomedical research.

Decellularized extracellular matrix biomaterials for regenerative therapies: Advances, challenges and clinical prospects

Tissue engineering and regenerative medicine have shown potential in the repair and regeneration of tissues and organs via the use of engineered biomaterials and scaffolds. However, current constructs face limitations in replicating the intricate native microenvironment and achieving optimal regenerative capacity and functional recovery. To address these challenges, the utilization of decellularized tissues and cell-derived extracellular matrix (ECM) has emerged as a promising approach. These biocompatible and bioactive biomaterials can be engineered into porous scaffolds and grafts that mimic the structural and compositional aspects of the native tissue or organ microenvironment, both in vitro and in vivo. Bioactive dECM materials provide a unique tissue-specific microenvironment that can regulate and guide cellular processes, thereby enhancing regenerative therapies. In this review, we explore the emerging frontiers of decellularized tissue-derived and cell-derived biomaterials and bio-inks in the field of tissue engineering and regenerative medicine. We discuss the need for further improvements in decellularization methods and techniques to retain structural, biological, and physicochemical characteristics of the dECM products in a way to mimic native tissues and organs. This article underscores the potential of dECM biomaterials to stimulate in situ tissue repair through chemotactic effects for the development of growth factor and cell-free tissue engineering strategies. The article also identifies the challenges and opportunities in developing sterilization and preservation methods applicable for decellularized biomaterials and grafts and their translation into clinical products.

The matrix microenvironment influences but does not dominate tissue-specific stem cell lineage differentiation

Mesenchymal stem cells (MSCs) play a pivotal role in tissue engineering and regenerative medicine, with their clinical application often hindered by cell senescence during ex vivo expansion. Recent studies suggest that MSC-deposited decellularized extracellular matrix (dECM) offers a conducive microenvironment that fosters cell proliferation and accentuates stem cell differentiation. However, the ability of this matrix environment to govern lineage differentiation of tissue-specific stem cells remains ambiguous. This research employs human adipose-derived MSCs (ADSCs) and synovium-derived MSCs (SDSCs) as models for adipogenesis and chondrogenesis differentiation pathways, respectively. Genetically modified dECM (GMdECM), produced by SV40LT-transduced immortalized cells, was studied for its influence on cell differentiation. Both types of immortalized cells displayed a reduction in chondrogenic ability but an enhancement in adipogenic potential. ADSCs grown on ADSC-deposited dECM showed stable chondrogenic potential but increased adipogenic capacity; conversely, SDSCs expanded on SDSC-generated dECM displayed elevated chondrogenic capacity and diminished adipogenic potential. This cell-dependent response was confirmed through GMdECM expansion, with SDSCs showing enhanced chondrogenesis. However, ADSCs did not exhibit improved chondrogenic potential on GMdECM, suggesting that the matrix microenvironment does not dictate the final differentiation path of tissue-specific stem cells. Potential molecular mechanisms, such as elevated basement membrane protein expression in GMdECMs and dynamic TWIST1 expression during expansion and chondrogenic induction, may underpin the strong chondrogenic differentiation of GMdECM-expanded SDSCs.

Single-cell transcriptomics implicates the FEZ1-DKK1 axis in the regulation of corneal epithelial cell proliferation and senescence

Limbal stem/progenitor cells (LSC) represent the source of corneal epithelium renewal. LSC proliferation and differentiation are essential for corneal homeostasis, however, the regulatory mechanism remains largely unexplored. Here, we performed single-cell RNA sequencing and discovered proliferation heterogeneity as well as spontaneously differentiated and senescent cell subgroups in multiply passaged primary LSC. Fasciculation and elongation protein zeta 1 (FEZ1) and Dickkopf-1 (DKK1) were identified as two significant regulators of LSC proliferation and senescence. These two factors were mainly expressed in undifferentiated corneal epithelial cells (CECs). Knocking down the expression of either FEZ1 or DKK1 reduced cell division and caused cell cycle arrest. We observed that DKK1 acted as a downstream target of FEZ1 in LSC and that exogenous DKK1 protein partially prevented growth arrest and senescence upon FEZ1 suppression in vitro. In a mouse model of corneal injury, DKK1 also rescued the corneal epithelium after recovery was inhibited by FEZ1 suppression. Hence, the FEZ1-DKK1 axis was required for CEC proliferation and the juvenile state and can potentially be targeted as a therapeutic strategy for promoting recovery after corneal injury.

Microenvironmental Stiffness Directs Chondrogenic Lineages of Stem Cells from the Human Apical Papilla via Cooperation between ROCK and Smad3 Signaling

Cell-based cartilage tissue engineering faces a great challenge in the repair process, partly due to the special physical microenvironment. Human stem cell from apical papilla (hSCAP) shows great potential as seed cells because of its versatile differentiation capacity. However, whether hSCAP has potent chondrogenic differentiation ability in the physical microenvironment of chondroid remains unknown. In this study, we fabricated poly(dimethylsiloxane) (PDMS) substrates with different stiffnesses and investigated the chondrogenic differentiation potential of hSCAPs. First, we found that hSCAPs cultured on soft substrates spread more narrowly accompanied by cortical actin organization, a hallmark of differentiated chondrocytes. On the contrary, stiff substrates were favorable for cell spreading and stress fiber formation. More importantly, the increased chondrogenic differentiation of hSCAPs seeded on soft substrates was confirmed by characterizing increased extracellular proteoglycan aggregation through Alcian blue staining and Safranin O staining and enhanced markers toward chondrogenic differentiation including SRY-box transcription factor 9 (Sox9), type II collagen (Col2), and aggrecan in both normal α-minimum essential medium (αMEM) and specific chondrogenic medium (CM) culture conditions. Then, we investigated the mechanosensing/mechanotransduction governing the chondrogenic differentiation of hSCAPs in response to different stiffnesses and found that stiffness-sensitive integrin β1 and focal adhesion kinase (FAK) were essential for mechanical signal perception and were oriented at the start of mechanotransduction induced by matrix stiffness. We next showed that the increased nuclear accumulation of Smad3 signaling and target Sox9 facilitated the chondrogenic differentiation of hSCAPs on the soft substrates and further verified the importance of Rho-associated protein kinase (ROCK) signaling in regulating chondrogenic differentiation and its driving factors, Smad3 and Sox9. By using SIS3, the specific inhibitor of p-Smad3, and miRNA targeting Rho-associated protein kinase 1 (ROCK-1), we finally confirmed the importance of ROCK/Smad3/Sox9 axis in the chondrogenic differentiation of hSCAPs in response to substrate stiffness. These results help us to increase the understanding of how microenvironmental stiffness directs chondrogenic differentiation from the aspects of mechanosensing, mechanotransduction, and cell fate decision, which will be of great value in the application of hSCAPs in cartilage tissue engineering.

Immortalization Reversibility in the Context of Cell Therapy Biosafety

Immortalization (genetically induced prevention of replicative senescence) is a promising approach to obtain cellular material for cell therapy or for bio-artificial organs aimed at overcoming the problem of donor material shortage. Immortalization is reversed before cells are used in vivo to allow cell differentiation into the mature phenotype and avoid tumorigenic effects of unlimited cell proliferation. However, there is no certainty that the process of de-immortalization is 100% effective and that it does not cause unwanted changes in the cell. In this review, we discuss various approaches to reversible immortalization, emphasizing their advantages and disadvantages in terms of biosafety. We describe the most promising approaches in improving the biosafety of reversibly immortalized cells: CRISPR/Cas9-mediated immortogene insertion, tamoxifen-mediated self-recombination, tools for selection of successfully immortalized cells, using a decellularized extracellular matrix, and ensuring post-transplant safety with the use of suicide genes. The last process may be used as an add-on for previously existing reversible immortalized cell lines.

Matrix from urine stem cells boosts tissue-specific stem cell mediated functional cartilage reconstruction

Articular cartilage has a limited capacity to self-heal once damaged. Tissue-specific stem cells are a solution for cartilage regeneration; however, ex vivo expansion resulting in cell senescence remains a challenge as a large quantity of high-quality tissue-specific stem cells are needed for cartilage regeneration. Our previous report demonstrated that decellularized extracellular matrix (dECM) deposited by human synovium-derived stem cells (SDSCs), adipose-derived stem cells (ADSCs), urine-derived stem cells (UDSCs), or dermal fibroblasts (DFs) provided an ex vivo solution to rejuvenate human SDSCs in proliferation and chondrogenic potential, particularly for dECM deposited by UDSCs. To make the cell-derived dECM (C-dECM) approach applicable clinically, in this study, we evaluated ex vivo rejuvenation of rabbit infrapatellar fat pad-derived stem cells (IPFSCs), an easily accessible alternative for SDSCs, by the abovementioned C-dECMs, in vivo application for functional cartilage repair in a rabbit osteochondral defect model, and potential cellular and molecular mechanisms underlying this rejuvenation. We found that C-dECM rejuvenation promoted rabbit IPFSCs' cartilage engineering and functional regeneration in both ex vivo and in vivo models, particularly for the dECM deposited by UDSCs, which was further confirmed by proteomics data. RNA-Seq analysis indicated that both mesenchymal-epithelial transition (MET) and inflammation-mediated macrophage activation and polarization are potentially involved in the C-dECM-mediated promotion of IPFSCs' chondrogenic capacity, which needs further investigation.

Expression of extracellular matrix components in the meibomian gland

Purpose

Extracellular matrix (ECM) is a key component of the stem cell local microenvironment. Our study aims to explore the periglandular distribution of major components of ECM in the Meibomian gland (MG).

Methods

Human eyelids and mouse eyelids were collected and processed for immunofluorescence staining.

Results

Human MG tissues stained positive for collagen IV α1, collagen IV α2, collagen IV α5, and collagen IV α6 around the acini and duct, but negative for collagen IV α3 and collagen IV α4. The mouse MG were stained positive for the same collagen IV subunits as early as postnatal day 15. Laminin α2, laminin β1 and perlecan stained the regions surrounding the acini and the acinar/ductal junction in the human MG, but not the region around the duct. Tenascin-C was found specifically located at the junctions between the acini and the central ducts. Neither agrin nor endostatin was found in the human MG tissues.

Conclusion

The ECM expresses specific components in different regions around the MG, which may play a role in MG stem cell regulation, renewal, and regeneration.

Construction and identification of an immortalized rat intestinal smooth muscle cell line

BACKGROUND

Although intestinal smooth muscle cells (ISMCs) play an important role in the remodeling of the intestinal structure, considerably less is known about the molecular mechanisms that mediate the development and growth of ISMCs. A possible reason for this lag is the lack of cell lines that recapitulate ISMCs in vivo.

METHODS

In this study, we separated the primary ISMCs from the rat intestinal tract and integrated the Simian Vacuolating virus 40 Large T antigen (SV40 LT) gene into the genome of the primary ISMC to construct an immortalized cell line named ISMC-Hc.

KEY RESULTS

ISMC-Hc proliferated persistently without any signs of senescence up to 50 passages and without neoplasticity. Analysis of the genome isolated from ISMC-Hc confirmed that the SV40LT gene recombined in the genome, and mRNA reverse transcription PCR suggested that SV40LT could be expressed normally. In addition, ISMC-Hc had few morphological differences compared with the primary ISMC. Furthermore, ISMC-Hc showed the expression of the specific protein markers (alpha-smooth muscle actin and desmin) through immunofluorescence analysis. Further studies showed that ISMC-Hc had enhanced contractility and expressed the glial-derived neurotrophic factor, nerve growth factor, ciliary neurotrophic factor, and leukemia inhibitory factor after co-stimulation with IL-1 beta and TNF-alpha.

CONCLUSIONS AND INFERENCES

ISMC-Hc showed characteristics similar to that of primary ISMC and can be used as an in vitro model to explore the cellular and molecular mechanisms of ISMC. Additionally, the immortalized ISMCs could help investigate the basic functional mechanisms of intestinal diseases.

Integrated regulation of chondrogenic differentiation in mesenchymal stem cells and differentiation of cancer cells

Chondrogenesis is the formation of chondrocytes and cartilage tissues and starts with mesenchymal stem cell (MSC) recruitment and migration, condensation of progenitors, chondrocyte differentiation, and maturation. The chondrogenic differentiation of MSCs depends on co-regulation of many exogenous and endogenous factors including specific microenvironmental signals, non-coding RNAs, physical factors existed in culture condition, etc. Cancer stem cells (CSCs) exhibit self-renewal capacity, pluripotency and cellular plasticity, which have the potential to differentiate into post-mitotic and benign cells. Accumulating evidence has shown that CSCs can be induced to differentiate into various benign cells including adipocytes, fibrocytes, osteoblast, and so on. Retinoic acid has been widely used in the treatment of acute promyelocytic leukemia. Previous study confirmed that polyploid giant cancer cells, a type of cancer stem-like cells, could differentiate into adipocytes, osteocytes, and chondrocytes. In this review, we will summarize signaling pathways and cytokines in chondrogenic differentiation of MSCs. Understanding the molecular mechanism of chondrogenic differentiation of CSCs and cancer cells may provide new strategies for cancer treatment.

Decellularized extracellular matrix mediates tissue construction and regeneration

Contributing to organ formation and tissue regeneration, extracellular matrix (ECM) constituents provide tissue with three-dimensional (3D) structural integrity and cellular-function regulation. Containing the crucial traits of the cellular microenvironment, ECM substitutes mediate cell-matrix interactions to prompt stem-cell proliferation and differentiation for 3D organoid construction in vitro or tissue regeneration in vivo. However, these ECMs are often applied generically and have yet to be extensively developed for specific cell types in 3D cultures. Cultured cells also produce rich ECM, particularly stromal cells. Cellular ECM improves 3D culture development in vitro and tissue remodeling during wound healing after implantation into the host as well. Gaining better insight into ECM derived from either tissue or cells that regulate 3D tissue reconstruction or organ regeneration helps us to select, produce, and implant the most suitable ECM and thus promote 3D organoid culture and tissue remodeling for in vivo regeneration. Overall, the decellularization methodologies and tissue/cell-derived ECM as scaffolds or cellular-growth supplements used in cell propagation and differentiation for 3D tissue culture in vitro are discussed. Moreover, current preclinical applications by which ECM components modulate the wound-healing process are reviewed.

Stem cells immortalized by hTERT perform differently from those immortalized by SV40LT in proliferation, differentiation, and reconstruction of matrix microenvironment

Although matrix microenvironment has the potential to improve expanded stem cell proliferation and differentiation capacity, decellularized extracellular matrix (dECM) deposited by senescent cells does not contribute to the rejuvenation of adult stem cells, which has become a barrier to personalized stem cell therapy. Genetic modification is an effective strategy to protect cells from senescence but it carries the increased risk of malignant transformation and genetic instability. In this study, lentivirus carrying either human telomerase reverse transcriptase (hTERT) or simian virus 40 large T antigen (SV40LT) was used to transduce human infrapatellar fat pad-derived stem cells (IPFSCs). We found that virus transduction modified the proliferative, chondrogenic, and adipogenic abilities of IPFSCs. Interestingly, dECM deposited by immortalized cells significantly influenced replicative senescent IPFSCs in proliferation and differentiation preference, the effect of which is hinged on the approach of immortalization using either SV40LT or hTERT. Our findings indicate both dECM expansion and immortalization strategies can be used for replicative senescent adult stem cells' proliferation and lineage-specific differentiation, which benefits future stem cell-based tissue regeneration. This approach may also work for adult stem cells with premature senescence in elderly/aged patients, which needs further investigation. STATEMENT OF SIGNIFICANCE: Adult stem cells are a promising solution for autologous cell-based therapy. Unfortunately, cell senescence due to donor age and/or ex vivo expansion prevents clinical application. Recent progress with decellularized extracellular matrix provides a potential for the rejuvenation of senescent stem cells by improving their proliferation and differentiation capacities. Given the fact that the young matrix can provide a healthy and energetic microenvironment, in this study, two approaches using lentivirus transduction of hTERT and SV40LT were compared. The goal was to immortalize donor cells for deposition of decellularized extracellular matrix. The matrix was demonstrated to contribute diverging effects on the chondrogenic and adipogenic differentiation of expanded stem cells and exhibited proliferation benefits as well. These findings provide an invaluable asset for stem cell-based tissue regeneration.

The Art of Engineering Biomimetic Cellular Microenvironments

Cells and their surrounding microenvironment exist in dynamic reciprocity, where bidirectional feedback and feedforward crosstalk drives essential processes in development, homeostasis, and disease. With the ongoing explosion of customizable biomaterial innovation for dynamic cell culture, an ever-expanding suite of user-programmable scaffolds now exists to probe cell fate in response to spatiotemporally controlled biophysical and biochemical cues. Here, we highlight emerging trends in these efforts, emphasizing strategies that offer tunability over complex network mechanics, present biomolecular cues anisotropically, and harness cells as physiochemical actuators of the pericellular niche. Altogether, these material advances will lead to breakthroughs in our basic understanding of how cells interact with, integrate signals from, and influence their surrounding microenvironment.

Unfavorable Contribution of a Tissue-Engineering Cartilage Graft to Osteochondral Defect Repair in Young Rabbits

A stem cell-based tissue-engineering approach is a promising strategy for treatment of cartilage defects. However, there are conflicting data in the feasibility of using this approach in young recipients. A young rabbit model with an average age of 7.7 months old was used to evaluate the effect of a tissue-engineering approach on the treatment of osteochondral defects. Following in vitro evaluation of proliferation and chondrogenic capacity of infrapatellar fat pad-derived stem cells (IPFSCs) after expansion on either tissue culture plastic (TCP) or decellularized extracellular matrix (dECM), a premature tissue construct engineered from pretreated IPFSCs was used to repair osteochondral defects in young rabbits. We found that dECM expanded IPFSCs exhibited higher proliferation and chondrogenic differentiation compared to TCP expanded cells in both pellet and tissue construct culture systems. Six weeks after creation of bilateral osteochondral defects in the femoral trochlear groove of rabbits, the Empty group (left untreated) had the best cartilage resurfacing with the highest score in Modified O’Driscoll Scale (MODS) than the other groups; however, this score had no significant difference compared to that of 15-week samples, indicating that young rabbits stop growing cartilage once they reach 9 months old. Interestingly, implantation of premature tissue constructs from both dECM and TCP groups exhibited significantly improved cartilage repair at 15 weeks compared to those at six weeks (about 9 months old), indicating that a tissue-engineering approach is able to repair adult cartilage defects. We also found that implanted pre-labeled cells in premature tissue constructs were undetectable in resurfaced cartilage at both time points. This study suggests that young rabbits (less than 9 months old) might respond differently to the classical tissue-engineering approach that is considered as a potential treatment for cartilage defects in adult rabbits.