The Joel A. DeLisa Lecture on regenerative rehabilitation was presented by Dr. Thomas Rando on February 27, 2025, at the Association of Academic Physiatrists Annual Scientific Meeting. This article follows the key themes presented in that lecture, exploring the regenerative potential of exercise as a biophysical stimulus and focusing on its ability to modulate muscle stem cell (MuSC) function and enhance tissue repair following muscle injury. In aged mice, exercise restores youthful properties to MuSCs, thereby enhancing regenerative capacity that declines with age. In models of volumetric muscle loss (VML), exercise improves the engraftment and integration of transplanted MuSCs by promoting myogenesis, angiogenesis, and reinnervation. Additionally, exercise shifts systemic and local immune responses toward a pro-regenerative state, enhancing stem cell function across multiple tissues. Exercise acts as a potent, non-invasive regenerative intervention with direct effects on stem cell biology and tissue repair. These findings highlight the potential for integrating exercise-based rehabilitation with emerging biologic therapies in clinical practice, offering new strategies for improving recovery after injury. In this context, physiatrists and physical therapists will play a central role in the emerging field of regenerative rehabilitation.

Critical-sized bone defects (CSD) remain a major clinical challenge due to three interrelated barriers: inadequate mechanical support, insufficient osteogenic induction, and impaired angiogenesis, all of which hinder effective regeneration. To tackle these, we developed a dual-network bioactive scaffold, ermd bFGF@CB-gel, based on a chondroitin sulfate methacryloyl/bacterial cellulose gel (CB-gel) which synergistically combines three key properties: i) a photocurable biomimetic mineralized scaffold (CB-gel) for in situ bone repair with mechanical support and a bone-ECM-mimicking microenvironment for delivering bone marrow mesenchymal stem cells (BMSCs); ii) a bio-nano carrier (BC) for sustained release of bFGF which enhances the adhesion and proliferation via EGFL/Itga2b pathway, strengthens osteogenic differentiation and mineralization by activating the COMP/PI3K/AKT pathway of rat BMSCs; iii) bFGF released by the dual-network promotes migration and angiogenesis of microvascular endothelial cells by combining FGFR to activate the PI3K/AKT/eNOS pathway. In a rat CSD model, the bFGF@CB-gel achieved a statistically significant increase in new bone volume, as quantified by micro-CT, and enhanced vascular density, evaluated via immunohistochemical staining. These findings highlight the potential of bFGF@CB-gel as an effective local delivery system of BMSCs via linking biomechanics, molecular signaling, and cellular activity, which moves beyond simplistic function stacking to a rational, synergistic design for bone regeneration in CSD, addressing key challenges in reconstructive surgery.

Therapeutic angiogenesis (TA) is a promising strategy for treating ischemic diseases, mainly by targeting the angiogenesis pathways and cells, particularly VEGF and endothelial progenitor cells. Although stem cell therapy has been extensively investigated, its clinical translation remains limited by challenges such as poor cell retention, low survival rates, and inefficient integration. In this review, we propose a mechanism-based framework of angiogenesis to discuss how biomaterials act synergistically with stem cells mainly through two distinct pathways: enhancing paracrine capacity and promoting direct differentiation of vascular lineage cells for vascular repair. Firstly, we go through the scientific literature and clinical studies, and summary the researches on biomaterials serve as artificial microenvironments to improve the retention and secretory function of mesenchymal stem cells (MSCs) and adipose-derived stem cells (ADSCs), thereby maximizing the release of angiogenic factors such as VEGF, bFGF, NGF, microRNA and so on. Secondly, we explore how functionalized biomaterials guide the in situ recruitment of endothelial progenitor cells (EPCs) and support the structural maturation of induced pluripotent stem cell (iPSC)-derived endothelial cells. By integrating these mechanism-driven approaches, we offer new perspectives on future directions for preclinical research and clinical translation of biomaterial-based therapies. Overall, this review has examined the role of individual stem cells and biomaterials, especially enhanced angiogenesis by stem cells focusing on their mechanisms of action and preclinical and clinical applications. We further discussed the challenges encountered by stem cell therapy in advancing to the stage of clinical transformation and considered future prospects.

Mitochondria are increasingly recognized as central regulators of vascular health, shaping endothelial cell function through roles that extend far beyond energy production. In addition to coordinating redox balance, calcium dynamics, and biosynthetic support, recent studies have revealed that mitochondria participate in intercellular communication, with evidence of transfer events emerging in vascular contexts. Parallel efforts have advanced the deliberate delivery of exogenous mitochondria from preclinical proof-of-principle studies to first-in-human trials, demonstrating that freshly isolated organelles can be harvested and administered in real-time to critically ill patients with favorable early outcomes. The mechanisms underlying these benefits remain incompletely defined, and strategies for efficient and scalable delivery are still emerging. In this review, we prioritize recent evidence linking mitochondrial function to endothelial cell physiology, highlight the nascent but growing field of mitochondrial transfer in the vasculature, and examine how mitochondrial transplantation is evolving from experimental concept to clinical translation. Together, these advances point to new therapeutic avenues for preserving vascular integrity and treating disease.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have potential applications in treating cardiovascular disease but are currently limited in their clinical translation. This can be attributed in large part to the complex molecular and cellular interactions that underly cardiac differentiation, with current differentiation approaches yielding heterogeneous outcomes due to inadequate understanding and control of these interactions. We hypothesize that clonal lineage-dependent responses to differentiation contribute to these heterogeneous outcomes, and as such cardiac differentiations can be improved by tracking and controlling for hiPSC clonal heterogeneity, a variable often overlooked in current differentiation approaches. "Fate priming", wherein clonal lineage identity determines differentiation fate, has been demonstrated in other stem cell differentiation pathways. We investigated fate priming in hiPSC cardiac differentiation using the ClonMapper cell barcoding platform to label, track, and isolate distinct hiPSC lineages from the same cell line. We show that certain hiPSC lineages preferentially differentiate into hiPSC-CMs or non-CMs. After isolating lineages with apparent fate priming, we found significant differences in cardiac differentiation outcomes between these single-clone populations and heterogeneous, multi-clone hiPSC populations. These findings indicate that lineage identity influences hiPSC cardiac differentiation outcomes.

Radiation therapy induces DNA damage primarily through reactive oxygen species, leading to cancer cell apoptosis. However, intratumoral heterogeneity and spatial dose variations often result in the survival of polyploid giant cancer cells (PGCCs), a therapy-resistant subpopulation characterized by multinucleation, genetic instability, and stem-like features. Particularly in malignant breast cancer, PGCCs contribute to recurrence by adopting a dormant yet invasive phenotype. Despite their clinical relevance, reliable tools to identify or characterize these cells remain lacking. Here, we present a nanomechanical single-cell profiling platform that enables high-resolution mechanomics of radiation-induced PGCCs. Through integrated cytoskeletal imaging and nanoscale stiffness mapping, we identify a distinct mechanical dormancy state, marked by cortical actin remodeling, nuclear enlargement, and biomechanical stiffening. This dormant mechanotype is coupled with suppressed proliferation yet sustained expression of invasion-associated markers, representing a latent therapeutic threat. Our findings position mechanical dormancy as a mechanobiological hallmark of radiation resistance and propose a predictive framework for optimizing radiotherapy thresholds. This platform enables mechanotype-guided stratification and precision-targeted intervention in radiation-refractory cancer.

Exagamglogene autotemcel (exa-cel) is a one-time nonviral gene-edited therapy approved in the United States (US) for treatment of patients aged ≥12 with transfusion-dependent β-thalassemia (TDT). Standard of care (SOC) for TDT includes regular red blood cell transfusions (RBCTs) and iron chelation therapy. This study estimated long-term clinical outcomes and cost-effectiveness of exa-cel vs. SOC among patients with TDT in the US.

Pharmacological reversal of abnormal promoter DNA hypermethylation at tumor suppressor genes (TSGs) is a key therapeutic paradigm for cancer management. However, the clinical efficacy of currently approved nucleoside analog hypomethylating agents (HMAs) is limited by dose-dependent toxicity and high resistance rates. Nonnucleoside, DNA methyltransferase 1 (DNMT1)-selective inhibitors offer a promising alternative. To date, only limited chemotypes, exemplified by the dicyanopyridine derivative GSK3685032 (GSK5032), have demonstrated translatable DNMT1 inhibition, with resistance emerging upon prolonged exposure. To address these limitations, we employ structure-guided scaffold hopping and chemical optimization to develop a series of DNMT1 inhibitors (DNMT1i) featuring a bicyclic 7-azaindole scaffold. We identify DMI46, a potent enzymatic DNMT1i capable of reversing cancer-specific DNA methylation abnormalities and TSG silencing, leading to robust antileukemic effects and favorable tolerability. Cryoelectron microscopy (cryo-EM) studies reveal that the 7-azaindole inhibitor exhibits enhanced intercalation into hemi-methylated CpG dyads and increased minor-groove contacts within the DNMT1/hemimethylated DNA complex compared to GSK5032. These structural features enable sustained DNMT1 targeting and significant antiproliferative activity of DMI46 in GSK5032-resistant acute myeloid leukemia (AML) cells. We also demonstrate DMI46's capacity to overcome AML resistance to nucleoside-based HMAs both in vitro and in vivo. These findings introduce a distinct DNMT1i chemotype with enhanced on-target engagement and broad applicability against HMA-resistant AML.

Microbial-derived short-chain fatty acids regulate a variety of pathways in the healthy colonic mucosa. In particular, butyrate serves as the primary energy source for colonocytes and regulates gene transcription by stabilizing the transcription factor hypoxia-inducible-factors (HIF) and functioning as a histone deacetylase (HDAC) inhibitor. A limitation of butyrate as a therapeutic is its rapid metabolism in differentiated colonocytes. Furthermore, intestinal stem cells (ISCs) respond differently to butyrate, preferentially using glucose for energy procurement. To address these limitations, we explored metabolite mimicry to identify compounds with potent or selective biological responses within the butyrate pathway(s). We found an analog, 3-chlorobutyrate (3-Cl BA), that significantly enhances epithelial barrier formation and wound healing in vitro. Mechanistically, we revealed that 3-Cl BA is a potent HDAC inhibitor. Furthermore, unlike butyrate, 3-Cl BA does not stabilize HIF and it is not used as metabolic fuel. In vivo studies in a dextran sulfate sodium-colitis model revealed that contrary to butyrate, 3-Cl BA is protective. Studies in stem-like colonoids demonstrated that only butyrate inhibits ISC proliferation and differentiation. Furthermore, it was recently reported that HIF stabilization inhibits ISCs activity. Given the fact that butyrate but not 3-Cl BA stabilizes HIF, we surmised that 3-Cl BA would circumvent these detrimental functional consequences. We demonstrate here that pharmacologic HIF stabilization inhibits colonoid differentiation and that genetic loss of HIF significantly promotes ISC differentiation. This study reveals a promising butyrate analog protective in colitis and demonstrates the advantages of metabolite mimicry to dissect selective biological functions from major metabolites in the gut.

Colonic mucus forms a critical barrier to intestinal contents, providing the protection necessary for intestinal and organismal health. The mucus is composed of gel-forming mucin secreted by goblet cells residing in the epithelial layer lining the colon; yet, our knowledge of many of the attributes and functions of mucus and the goblet cells remains limited. A planar array of colonic cryptlike structures with a thick covering of goblet cell-generated mucus was developed to mimic the differentiated colonic epithelium and provide an easily accessible physiologic mucus layer for the evaluation of mucus barrier function in response to intestinal microbiota and toxins. The human microphysiological system (MPS) was created using an impermeable thin film patterned with a geometrical array of a 10 μm × 10 μm scale through holes overlaid with collagen and primary colonic stem cells. The array dimensions, collagen thickness, and growth factor concentration were optimized to assess the cell density, proliferation, migration, differentiation, and mucus thickness. A 175 μm center-to-center distance between the through holes or stem cell niches and a collagen thickness of 10 μm were found to be optimal to enable long-term culture (≥23 days) with a discrete stem/proliferative cell region and a differentiated cell zone enriched in goblet cells and supporting a 250 μm-thick adherent mucus layer. The mucus layer acted as an effective barrier to block the access of the Staphylococcus aureus α-hemolysin toxin to the epithelial cells as well as to protect the cell layer from both Staphylococcus aureus and Lactobacillus rhamnosus. The intestinal mucus MPS will be a useful tool for emulating the intestinal epithelium to study the interplay of stem cell renewal, goblet cell differentiation, mucus dynamics, and microbiota-mucus-host interactions.

Copyright: © 2026 Makovec et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Prostate gland cells can be transcriptionally and morphologically characterized as basal and luminal. About 30–40% of advanced prostate cancers (PC) harbor basal-like transcription programs. In castration-resistant PC (CRPC), studies indicate that basal and stem cell-like (SCL) tumors are major resistance mechanisms to androgen receptor (AR)-targeted therapies. SCL tumors have reduced AR activity and increased stem-cell activity that promotes tumor formation, which contributes to poor clinical outcomes. We determined that CREB5 is a key regulator of basal and SCL transcriptional programs and tumor-forming phenotypes in PC. Through in silico modeling of PC transcriptomes and several pre-defined PC signaling programs, CREB5 expression was best associated with basal-like gene signatures and SCL-associated genes in primary PC and CRPCs (n = 493 and 208). This included associations with FOSL1 and other AP-1 transcription factors. We further found that CREB5 interacted with AP-1 proteins and bound to the regulatory elements of AP-1 genes, suggesting a mechanistic role in regulating the activity of AP-1 genes. In AR-positive cells, CREB5 overexpression promoted cell colony growth with tumorigenic properties and increased tumor size in vivo. These findings implicate CREB5 as a driver of the transcriptional programs underlying AR-independent basal and SCL CRPC subtypes, and this activity is detectable in primary PC.

An aberration in cellular, especially plasma membrane (PM), cholesterol level is arguably the most critical targetable hallmark of colorectal cancer (CRC) and CRC stem cell (CRCSC) phenotypes. We recently identified StarD5 as an intracellular cholesterol transport protein that regulates PM cholesterol levels. Here, we show that StarD5 protein levels are significantly elevated in most human CRC tissues compared to adjacent normal mucosa, with a preferential increase in the epithelial compartment. Additionally, allograft growth in StarD5 knockout mice was largely unaffected. StarD5 levels were particularly elevated in CRCSCs compared to non-CRCSCs in several colon cancer cell lines and primary human CRC samples. Genetic knockdown of StarD5 (shRNA) (KD) inhibited the CRCSC phenotype in vitrogrowth and self-renewal (1°→3° spheroid formation), CRCSC maker levels, and sensitivity to 5-fluorouracil. Also, StarD5-depleted HT-29 cells showed a robust (40-fold) reduction in tumor formation (CRCSC characteristics) in vivo and CRCSC phenotype ex vivo, including CRCSC marker expression and spheroid formation (1°→3°). StarD5 inhibition also caused a significant increase in apoptosis induction. Mechanistically, PM cholesterol levels were significantly higher in CRCSCs than in non-CRCSCs, and StarD5 depletion decreased accessible PM cholesterol, particularly in specialized lipid raft domains. Finally, cholesterol depletion in the PM is critical for StarD5 KD's inhibition of the CRCSC phenotype as supplementation with low-density lipoprotein caused a significant reversal of the StarD5 KD effects on PM/raft cholesterol levels and CRCSC phenotype. Implications: Given StarD5's critical role in regulation of CRCSCs, translational research targeting StarD5 will lead to improved outcomes in patients with CRC.

Mesenchymal stem cells (MSCs) play a crucial role in cell therapy, but their efficacy diminishes with age. While biochemical methods like flow cytometry, immunoblotting, β-galactosidase labeling, and gene profiling are effective for screening MSC aging, mechanical factors also change with aging. After analyzing the transcriptomes of young and aged MSCs, we observed downregulation of adhesion-related genes and, based on those data, developed an integrin mechano-probe to measure integrin forces in MSCs. The probe's effectiveness was validated by mapping integrin forces in young and aged MSCs, revealing reduced integrin force signals in aged cells that correlated with downregulated expression of β1 integrins. This finding was further confirmed by flow cytometry and β-galactosidase staining. Overexpression of integrin β1 in aged MSCs restored mechanical signaling and increased p-ERK production, suggesting that the integrin β1/ERK pathway plays a role in rescuing the contractility of aged MSCs. Our mechano-probe enables distinguishing aged MSCs in a mixed pool of young and aged MSCs and identifying aged MSCs taken from mouse tissue. Integrin tension signals, as measured by a mechano-probe, may thus complement biochemical markers in assessing MSC aging.

The bone marrow (BM) microenvironment plays a crucial role in regulating hematopoiesis, yet the molecular changes associated with aging in humans remain poorly understood. Using single-cell RNA sequencing, we uncovered transcriptional shifts in BM endothelial cells (EC) and mesenchymal stromal cells (MSC) during aging. Aged sinusoidal EC exhibited a prothrombotic phenotype with compromised mitochondrial and vascular function. Additionally, we identified a novel arterial EC subset, emerging in aged individuals, characterized by RAB13 expression and associated with transcriptional regulatory processes. MSC from aged subjects displayed impaired matrix remodeling and epithelial-mesenchymal transition, driven partly by a subpopulation of THY1+ profibrotic cells absent in younger individuals. Finally, immunofluorescent imaging and spatial transcriptomics confirmed the presence of these aging-associated cells in BM samples from aged individuals. In summary, this work provides a comprehensive view of the transcriptional landscape, cellular interactions, and spatial organization of aged EC and MSC, offering novel insights and potential targets that could be exploited for preventing age-associated changes in humans.

ObjectiveThe meniscus has poor intrinsic healing capacity, particularly in avascular regions. Meniscal injury is strongly associated with progressive knee dysfunction, chronic pain, and accelerated osteoarthritis development. Current treatments, such as allografts and partial meniscectomy, are limited by donor scarcity and secondary joint degeneration. Therefore, this study aimed to develop a regenerative meniscal scaffold with integrated biomechanical and biological functionality.MethodsA biomimetic composite scaffold was fabricated via low-temperature three-dimensional printing using poly(D,L-lactic acid-co-trimethylene carbonate) and bacterial cellulose. Native meniscal architecture was reproduced using micro-computed tomography-based modeling, and interconnected porosity was designed to promote cell infiltration. Material integration employed dichloromethane as a shared solvent, enabling dual-ink (poly(D,L-lactic acid-co-trimethylene carbonate) + bacterial cellulose) co-printing. Scaffold performance was assessed using scanning electron microscopy morphology, porosity and water absorption assays, mechanical testing, Fourier-transform infrared spectroscopy, and in vitro cytocompatibility studies with rat bone mesenchymal stem cells.ResultsThe scaffold exhibited a tensile modulus of 16.6 MPa and compressive modulus of 2.97 MPa, closely matching native meniscal mechanics. Porosity reached 63.57% ± 5.72%, supporting cell adhesion, while water absorption exceeded 138% after 7 days. Notably, the scaffold exhibited temperature-responsive shape memory behavior, allowing minimally invasive implantation and anatomic recovery at 37°C. Bone mesenchymal stem cells exhibited 95% viability (live/dead staining), significant proliferation (cell counting kit-8), and spontaneous chondrogenic differentiation (SRY-box transcription factor 9/collagen type II (SOX9/COLII) expression) without exogenous induction.ConclusionThis three-dimensional-printed poly(D,L-lactic acid-co-trimethylene carbonate)/bacterial cellulose composite scaffold integrates biomimetic mechanics, shape-memory functionality, and pro-chondrogenic bioactivity, offering a promising strategy for meniscal regeneration. Further in vivo studies are warranted to confirm long-term efficacy and clinical translational potential.

To identify the optimal transplantation route for enhancing homing of mesenchymal stem cells (MSCs) to the kidney, thereby ameliorating rat Adriamycin nephropathy (AN). In vivo animal imaging revealed that ultrasound-guided intrarenal-arterial transplantation of GFP-MSCs markedly increased the number of MSCs homing to the kidney compared with the intravenous injection (IV) and renal parenchyma (RP) routes. Multimodal ultrasonography revealed that the renal artery (RA) group exhibited reduced renal parenchymal echogenicity and significantly increased cortical microvascular perfusion compared to the Adriamycin (ADR), IV, and RP groups. Hematoxylin and eosin (H&E) staining, Masson staining, and electron microscopy revealed that the RA group had an enlarged glomerular volume, diminished renal interstitial fibrosis, and attenuated mitochondrial damage compared to the ADR, IV, and RP groups. Western blotting, qRT-PCR and immunohistochemistry further indicated that the RA group mitigated rat AN by downregulating the JAK2, AKT1, and STAT3 signaling pathways more effectively than the ADR, IV, and RP groups did. The above findings indicate that under ultrasound guidance, MSCs transplanted via the renal artery can ameliorate AN-induced renal injury by acting on the JAK/STAT signaling pathway.

While the apolipoprotein E (APOE) ε4 allele is a major risk factor for Alzheimer's disease (AD), the role of translocase of outer mitochondrial membrane 40 (TOMM40)-an adjacent gene involved in mitochondrial protein import-is not known.

Model systems that mimic human cardiac structure and function are essential for the development of novel diagnostics and effective treatments for cardiovascular diseases. While non-human vertebrate models, from zebrafish to pig, remain vital to cardiovascular research, the translatability of findings to human patients is often limited. Therefore, animal experiments should be supplemented with human model systems, including human induced pluripotent stem cell-derived cells, 3D engineered constructs, and last but not least, native tissue preparations and isolated primary cardiomyocytes. However, while human myocardium remains the gold standard, human heart tissue - and particularly tissue from control hearts-remains scarce, and its use in research is generally restricted to settings where tissue has been excised from diseased or failing hearts. While it is in principle possible to use tissue from rejected non-failing donor hearts that cannot be transplanted, legal hurdles (e.g., in Germany) can restrict the use of non-transplanted donor organs in research. Given the challenges associated with accessing and using human tissue in biomedical research, an integrated strategy towards combining non-human vertebrate models, in silico models, and human tissue-derived models is recommended, enhancing the chances of successful research and development, and helping bridge the gap between preclinical and clinical research.

Although mRNA therapy has achieved favorable outcomes, it still faces limitations such as poor stability and short duration of protein expression. In this study, we utilized a covalently closed circular RNA encoding bone morphogenetic protein-2 (BMP2 circRNA), which exhibits exceptional nuclease resistance and an extended half-life, thereby enabling sustained and efficient BMP2 protein expression. The BMP2 circRNA was encapsulated into biomimetic nanovesicles (BNVs) derived from bone marrow mesenchymal stem cells (BMSCs) using co-extrusion technology. These BNVs were then anchored onto the surface of micro-arc oxidized titanium (Ti-MAO) implants via polydopamine (PDA) adhesion, constructing a novel local gene delivery system. In vitro experiments confirmed that this system is not only efficiently internalized by cells but also evades lysosomal degradation, facilitating the sustained release of BMP2 protein. This, in turn, significantly promoted osteogenic gene expression and accelerated mineral deposition. Furthermore, in vivo animal studies demonstrated that the functionalized implant markedly enhanced bone regeneration, increasing both bone volume fraction and bone-to-implant contact. This study successfully integrated the inherent stability of circRNA with a biomimetic delivery strategy, offering an effective approach for improving implant osseointegration.

Sarcomeres are the fundamental contractile units of muscle. Despite their importance, sarcomere assembly remains poorly understood. We focused on Actn2, a protein which stabilizes the sarcomere by linking proteins to the Z-disk. During C2C12 differentiation into myoblasts, Actn2 protein levels remained constant. This finding suggested that Actn2 incorporation into the sarcomere arose from a post-translational mechanism. We hypothesized that the post-translational mechanism relied on phosphorylation. Alignment of Actn2 protein sequences from animals with three- or four-chambered hearts identified a conserved sequence, T308P309E310K311, that matches the consensus phosphorylation motif of the cell-cycle kinase CDK1. In vitro kinase assays showed that CDK1 phosphorylates Actn2 at T308. In contrast, CDK1 was unable to phosphorylate Actn2 when T308 was mutated to alanine (T308A). Using CRISPR-Cas9 gene editing, we created Actn2-T308A and phosphomimetic Actn2-T308D variants in C2C12 cells. C2C12 cells expressing Actn2-T308A differentiated rapidly and formed robust sarcomeres. However, C2C12 cells expressing Actn2-T308D failed to form organized sarcomeres. Curiously, Actn2-T308A cells were found to have less proliferative capacity than Actn2-T308D cells. Taken together, these results identify CDK1-dependent phosphorylation of Actn2-T308 as being important for sarcomere assembly. Moreover, the data also suggest a mechanism by which cell-cycle exit promotes sarcomere assembly.