Biology subjects

Han, W. M.

Publications and source records attributed to Han, W. M..

9 recordsLinked to original sources

bioRxiv2025

Aberrant Fibro-Adipogenic Progenitor Subpopulations Drive Volumetric Muscle Loss-Induced Fibrosis

Volumetric muscle loss (VML) injuries result in chronic fibrosis, inflammation, and persistent functional deficits. Fibro-adipogenic progenitor (FAP) cells are a heterogeneous, muscle-resident stromal cell population that play a crucial role in muscle regeneration, but also contribute to fibrosis in muscle disease. The role of FAPs in VML is not well established and may be critical target to ensure functional muscle regeneration after VML. We utilized a VML model in the mouse quadriceps to study the location, secretome, surface marker distribution, gene expression, and single-cell transcriptional profile of FAPs after VML. After VML, a subpopulation of FAPs highly expressed {beta}1-integrin and were elevated in the post-VML muscle tissue; these FAPs had increased fibrotic gene expression and increased myofibroblast differentiation potential. Transforming growth factor-{beta}1 (TGF-{beta}1) and tissue inhibitor of matrix metalloproteinase 1 (TIMP1) were identified as secreted proteins from VML derived FAPs that produced both pro-fibrotic and anti-myogenic signaling. These data establish an aberrant FAP sub-population that are elevated in VML injury and provides novel targets for future scarless muscle regeneration in VML.

pathology↗

bioRxiv2024

3D mechanical confinement directs muscle stem cell fate and function

Muscle stem cells (MuSCs) play a crucial role in skeletal muscle regeneration, residing in a niche that undergoes dimensional and mechanical changes throughout the regeneration process. This study investigates how three-dimensional (3D) confinement and stiffness encountered by MuSCs during the later stages of regeneration regulate their function, including stemness, activation, proliferation, and differentiation. We engineered an asymmetric 3D hydrogel bilayer platform with tunable physical constraints to mimic the regenerating MuSC niche. Our results demonstrate that increased 3D confinement maintains Pax7 expression, reduces MuSC activation and proliferation, inhibits differentiation, and is associated with smaller nuclear size and decreased H4K16ac levels, suggesting that mechanical confinement modulates both nuclear architecture and epigenetic regulation. MuSCs in unconfined two-dimensional (2D) environments exhibited larger nuclei and higher H4K16ac expression compared to those in more confined 3D conditions, leading to progressive activation, expansion, and myogenic commitment. This study highlights the importance of 3D mechanical cues in MuSC fate regulation, with 3D confinement acting as a mechanical brake on myogenic commitment, offering novel insights into the mechano-epigenetic mechanisms that govern MuSC behavior during muscle regeneration.

bioengineering↗

bioRxiv2022

Wnt7a Suppresses Adipogenesis of Skeletal Muscle Mesenchymal Stem Cells and Fatty Infiltration Through the Alternative Wnt-Rho-YAP/TAZ Signaling Axis

Intramuscular fatty infiltration in muscle injuries and diseases, caused by aberrant adipogenesis of fibro-adipogenic progenitors, negatively impacts function. Intramuscular delivery of Wnt7a offers a promising strategy to stimulate muscle regeneration but its effects on adipogenic conversion of fibro-adipogenic progenitors remain unknown. Here we show that Wnt7a inhibits adipogenesis of FAPs through the alternative Wnt-Rho-YAP/TAZ signaling that subsequently upregulates the canonical Wnt pathway. Furthermore, intramuscular injection of Wnt7a in vivo effectively suppresses fatty infiltration in mice. Our results collectively suggest Wnt7a as a potential protein-based therapeutic for inhibiting adipogenesis of FAPs and intramuscular fatty infiltration in pathological muscle injuries or diseases.

cell biology↗

bioRxiv2020

Regenerating motor neurons prime muscle stem cells for myogenesis by enhancing protein synthesis and mitochondrial bioenergetics

Throughout life, skeletal muscle, the arbiter of voluntary movements, is maintained by a population of skeletal muscle-dedicated stem cells, called muscle satellite cells (MuSCs). Similar to other adult stem cells, the function of MuSCs is tightly coordinated by the cellular and acellular components of their microenvironment, or the niche. While the processes that control the coupling of neurotransmission and muscle contraction have been well characterized, little is known on the reciprocal crosstalk between neural cells and MuSCs within the muscle microenvironment. Here, we report that mild peripheral nerve injury enhances MuSC myogenic function and muscle regeneration by synergistically augmenting MuSC mitochondrial bioenergetics and upregulating anabolic protein synthesis pathways. We also demonstrate that chronic disruption or degeneration of neuromuscular synapses, such as in muscular dystrophy and biological aging, abolishes MuSC and motor neuron interactions, causing significant deficits in muscle regeneration following injury. These results underscore the importance of neuromuscular junction and neural network as an essential niche of MuSCs. Determining the significance of MuSC-nerve interactions and their functional outcomes, as well as the possibility of modulating these connections, have important implications for our understanding of neuromuscular disease pathology and development of therapeutic interventions. HighlightsO_LIMild peripheral nerve injury increases muscle stem cell bioavailability of healthy muscle. C_LIO_LINerve perturbation stimulates myogenesis by enhancing protein synthesis and mitochondrial metabolism in young, healthy muscle. C_LIO_LISynergistic crosstalk within neuromuscular niche boosts muscle regeneration in young, healthy muscle. C_LIO_LIPositive influences from the neural network on muscle stem cells are abolished in pathological denervation manifested in dystrophic and aging muscle. C_LI

cell biology↗

bioRxiv2020

Transplantation of muscle stem cell mitochondria rejuvenates the bioenergetic function of dystrophic muscle

Mitochondrial dysfunction has been implicated in various pathologies, including muscular dystrophies. During muscle regeneration, resident stem cells, also known as muscle satellite cells (MuSCs), undergo myogenic differentiation to form de novo myofibers or fuse to existing syncytia. Leveraging this cell-cell fusion process, we postulated that mitochondria stemming from MuSCs could be transferred to myofibers during muscle regeneration to remodel the mitochondrial network and restore bioenergetic function. Here, we report that dystrophic MuSCs manifest significant mitochondrial dysfunction and fuse with existing dystrophic myofibers to propagate mitochondrial dysfunction during muscle repair. We demonstrate that by transplanting healthy donor MuSCs into dystrophic host muscle, the mitochondrial network (reticulum) and bioenergetic function can be rejuvenated. Conversely, when bioenergetically-compromised donor MuSCs are transplanted, improvements in mitochondrial organization and bioenergetic function were ablated in the dystrophic recipient. Overall, these data reveal a unique role of muscle stem cells as an essential regulator of myofiber mitochondrial homeostasis and a potential therapeutic target against mitochondrial myopathies.

cell biology↗

bioRxiv2020

Engineered Heterochronic Parabiosis in 3D Microphysiological System for Identification of Muscle Rejuvenating Factors

Exposure of aged mice to a young systemic milieu revealed remarkable rejuvenation effects on aged tissues, including skeletal muscle. Although some candidate factors have been identified, the exact identity and the underlying mechanisms of putative rejuvenating factors remain elusive, mainly due to the complexity of in vivo parabiosis. Here, we present an in vitro muscle parabiosis system that integrates young- and old-muscle stem cell vascular niche on a three-dimensional microfluidic platform designed to recapitulate key features of native muscle stem cell microenvironment. This innovative system enables mechanistic studies of cellular dynamics and molecular interactions within the muscle stem cell niche, especially in response to conditional extrinsic stimuli of local and systemic factors. We demonstrate that vascular endothelial growth factor (VEGF) signaling from endothelial cells and myotubes synergistically contribute to the rejuvenation of the aged muscle stem cell function. Moreover, with the adjustable on-chip system, we can mimic both blood transfusion and parabiosis and detect the time-varying effects of anti-geronic and pro-geronic factors in a single organ or multi-organ systems. Our unique approach presents a complementary in vitro model to supplement in vivo parabiosis for identifying potential anti-geronic factors responsible for revitalizing aging organs.

cell biology↗

bioRxiv2019

Wnt7a-releasing synthetic hydrogel enhances local skeletal muscle regeneration and muscle stem cell engraftment

Skeletal muscle possesses efficient ability to regenerate upon minor injuries, but its capacity to regenerate is severely compromised with traumatic injuries and muscle-associated diseases. Recent evidence suggests that skeletal muscle regeneration can be accelerated by transplantation of muscle satellite cells (MuSCs) or treatment with promyogenic factors, such as Wingless-type MMTV Integrated 7a (Wnt7a) protein. Although direct intramuscular injection is the simplest method to deliver MuSCs and Wnt7a for regenerative therapy, direct injection is not viable in many clinical cases where the structural integrity is severely compromised. To address this challenge, we engineered a synthetic poly(ethylene glycol) (PEG)-based hydrogel to facilitate the co-delivery of pro-myogenic factors, such as Wnt7a, and MuSCs to skeletal muscles affected by severe trauma or muscular dystrophies. Wnt7a release rate can be controlled by modulating the polymer density of the hydrogel, and this release rate can be further accelerated through the proteolytic degradation of the hydrogel. Treating cryo-injured tibialis anterior (TA) muscles with Wnt7a-loaded hydrogels resulted in an accelerated regenerative response, measured by increased muscle fiber cross-sectional area, bulk TA mass, and number of Pax7+ MuSCs at the injury site, compared to the TA muscles treated with Wnt7a-free hydrogels. Co-delivery of Wnt7a and primary MuSCs using the synthetic hydrogel to the cryo-injured TA muscles significantly increased cellular migration during the engraftment process. This work provides a synthetic biomaterial platform for advancing treatment strategies of skeletal muscle trauma and diseases, specifically in conditions where direct intramuscular injection may be challenging.

bioengineering↗

bioRxiv2018

Critical Limb Ischemia Induces Remodeling of Skeletal Muscle Motor Unit and Myonuclear- and Mitochondrial-Domains

Critical limb ischemia, the most severe form of peripheral artery disease, leads to extensive damage and alterations in skeletal muscle homeostasis. Although recent developments towards revascularization therapies have been introduced, there has been limited research into treatments for ischemic myopathy. To elucidate the regenerative mechanism of the muscle stem cell and its niche components in response to ischemic insults, we explored interactions between the vasculature, motor neuron, muscle fiber, and the muscle stem cell. We first investigated changes in the neuromuscular junction and motor neuron innervation following a surgical hindlimb ischemia model of critical limb ischemia in mice. Along with previous findings that support remodeling of the neuromuscular junction, we report that ischemic injury also causes significant alterations to the myofiber through a muscle stem cell-mediated increase of myonuclei number per fiber, a concomitant decrease in myonuclear domain size, and an increase in relative mitochondrial content per myonucleus. These results indicate that as a regenerative response to critical limb ischemia, myofibers exhibit myonuclear expansion to allow enhanced transcriptional support and an increase in mitochondrial content for bioenergetic need of the energy-demanding tissue regeneration.

physiology↗

bioRxiv2018

Muscle Stem Cell Niche Dysregulation in Volumetric Muscle Loss Injury

Skeletal muscle has a remarkable regenerative capacity; however, after volumetric muscle loss (VML) due to traumatic injury or surgery this regenerative response is significantly diminished, causing chronic functional deficits. The critical defect size at which the muscle will not functionally recover has not yet been established and subsequently, the relative contribution of crucial muscle components, including muscle stem cells and the muscle stem cell niche, are unknown. In this study, we created VML injuries of 2, 3, or 4 mm diameter, full-thickness defects in the mouse quadriceps. The 2, 3, and 4 mm injuries resulted in a defect of 5, 15, or 30% of the quadriceps mass, respectively. At 14 and 28 days after injury, histological analyses revealed injury size-dependent differences in myofiber morphology and fibrosis; the number of small myofibers increased with increasing injury size. The results showed that the 3 mm injury was at a threshold point, as myofibers were unable to bridge the defect, there was persistent fibrosis and inflammation, and significantly increased number of myofibers with centrally located nuclei. We then further investigated the 3 mm VML for nerve and vascular regeneration. These injured muscles were accompanied by a drastic increase in denervated neuromuscular junctions (NMJ), while assessment of angiogenesis via micro-CT analysis revealed a significant increase in vascular volume primarily from small diameter vessels after VML injury. Collectively, these data indicate that the spatial and temporal control of the fibrotic and neuromotor response are critical to regeneration and could be potential therapeutic targets, as they are the most dysregulated components of the muscle stem cell niche after VML.

bioengineering↗