Aug 2026· Frontiers in Neurology· Vol 17· 0 citations· 47 references
Medicine
TL;DR
Findings provide biochemical evidence of early alterations in extracellular matrix composition after stroke and reveal a systemic increase in HA concentration in the stroke group, while collagen levels remained unchanged.
Abstract
Background Previous studies about post-stroke peripheral structural remodeling have been focused on muscle fiber alterations, while extracellular matrix (ECM) remodeling in musculoskeletal tissues remains unclear. This study examines changes in extracellular matrix (ECM), specifically hyaluronan (HA) and collagen, in forelimb muscles following distal middle cerebral artery occlusion (dMCAO) in mice. Methods Twenty-two 8-week-old C57BL/6 mice (10 male, 12 female) were randomly assigned to the control group (n = 10; 4 male, 6 female) or the experimental group (n = 12; 6 male, 6 female). 4 weeks post-stroke, forelimb muscle samples were collected and analyzed for HA and collagen distribution and concentrations. Results HA concentrations were significantly elevated in both the left (stroke affected) forelimb muscles (63.74 ± 11.80 μg/g), and right (unaffected) forelimb muscles (64.16 ± 13.52 μg/g) of stroke mice compared to the controls (left: 50.07 ± 8.84 μg/g, p = 0.022; and right: 49.36 ± 12.22 μg/g, p = 0.015). No significant difference in HA levels was observed between the affected and unaffected sides of stroke mice (p = 0.905). Collagen concentrations did not differ significantly among groups (control left: 8.62 ± 2.91 μg/g; control right: 8.77 ± 1.35 μg/g; stroke-affected: 8.24 ± 2.11 μg/g; stroke-unaffected: 8.28 ± 2.45 μg/g). Conclusion The results revealed a systemic increase in HA concentration in the stroke group, while collagen levels remained unchanged. These findings provide biochemical evidence of early alterations in extracellular matrix composition after stroke.
BACKGROUND
Intramuscular fat grafting is used for soft tissue augmentation, yet its effects on muscle structure and function remain unclear.
OBJECTIVES
To evaluate structural and functional outcomes of intramuscular fat grafting using human lipoaspirate in a nude mouse model and assess its regenerative potential.
METHODS
Fifty-nine female athymic mice received 100 µL injections of low-density fat (n = 20), high-density fat (n = 20), or saline (n = 19) into hind limb muscles. In vivo grip strength was measured weekly for 6 months. Ex vivo mechanical testing was performed at study endpoint. Histology (H&E, Masson's trichrome) assessed muscle architecture and fibrosis, while immunofluorescence with human-specific markers evaluated graft persistence and cellular contribution.
RESULTS
No statistically significant differences in muscle strength were observed between groups. Peak in vivo hind limb grip strength ranged from 82-96 grams-force (gf), with saline-treated limbs generally demonstrating higher final values (78 gf) than high-density (61 gf) and low-density fat groups (50 gf). Ex vivo peak force measured 9.0 ± 1.8 N (saline), 8.0 ± 0.4 N (high-density), and 7.8 ± 0.5 N (low-density). At 6 months, most adipocytes were resorbed and replaced by collagen-rich extracellular matrix. Fibrosis was greater in high-density fat grafts (25.49 ± 3.28%) than saline (19.42 ± 4.05%) or low-density fat (19.61 ± 3.53%). Limited new muscle formation was observed, predominantly of mouse origin.
CONCLUSIONS
Intramuscular fat grafting resulted in transient graft survival followed by fibrosis and structural remodeling without functional improvement at 6 months, suggesting a primarily structural rather than regenerative role.
C. Kim, Bhavana Thota, Ariane Lazzarini et al.· Aesthetic surgery journal· 0 citations
Abstract Age‐related changes in large‐vessel biomechanics may contribute to neurovascular dysfunction and region‐specific biochemical remodeling in the brain, with important implications for female health. This study investigated the impact of aging on neck vasculature and brain lipid biochemistry in female C57BL/6NHsd mice by comparing young (12 weeks; n = 10) and middle‐aged (52 weeks; n = 10) cohorts using ultrasound imaging, histology, and mass spectrometry. In vivo ultrasound quantified carotid and jugular hemodynamics, including wall shear stress (WSS), circumferential cyclic strain (CCS), pulsatility index, and volumetric flow. Ex vivo assessments included spatial lipid mapping in vessels and brain, and histology staining to quantify elastin‐to‐collagen ratios. Middle‐aged females exhibited reduced carotid systolic velocity, systolic WSS, and body weight–normalized carotid volumetric flow compared to young controls, while pulsatility index and CCS showed non‐significant decreases. Histology revealed a reduction in the carotid elastin‐to‐collagen ratio, consistent with vascular remodeling. Lipidomic profiling identified age‐dependent shifts in lipid headgroups, including decreases across multiple brain lipid classes, increased N‐acylethanolamides, alongside increases in carotid cardiolipin and lysophosphatidylethanolamine. Hippocampal spectra showed clearer age‐related separation than whole‐brain analyses. Correlation analyses identified moderate to strong associations between vascular biomechanics and lipid features across tissues, supporting coordinated neurovascular and biochemical aging in female mice.
Allison R. Jones, A. Jarrahi, Kylee Karpowich et al.· Physiological Reports· 0 citations
The deep fascia surrounds skeletal muscles and contributes to force transmission and mechanical coordination, but its response to denervation remains unclear. This study investigated morphological and transcriptional adaptations of the deep fascia following sciatic nerve denervation in mice. Male C57BL/6J mice (n = 5–6/group) underwent unilateral sciatic nerve denervation or sham surgery. Fourteen days later, tibialis anterior (TA) muscle and overlying deep fascia (anterior crural fascia) were analyzed by histology and quantitative PCR. Denervation induced significant TA muscle atrophy with upregulation of inflammatory (Il6, p = 0.001), profibrotic (Tgfb, p < 0.001), and extracellular matrix (ECM)–related genes (Mmp2, p = 0.006; Col3a1, p = 0.005), and downregulation of regenerative factors (Fgf2, p < 0.001). Deep fascia thickness increased approximately 1.5‐fold (p = 0.012) and was accompanied by elevated Il6 (p < 0.001), Tgfb (p = 0.035), Col1a1 (p = 0.006), and Col3a1 (p = 0.003) expression and a higher proportion of collagen type III (p = 0.015). In conclusion, sciatic nerve denervation induces muscle atrophy and deep fascia thickening accompanied by extracellular matrix remodeling. These findings demonstrate coordinated yet tissue‐specific remodeling of skeletal muscle and deep fascia following sciatic nerve denervation.
Abstract Serial sarcomere number (SSN) is reduced following immobilization of a muscle in a shortened position in male rodents thereby impairing muscle contractile function. However, in female rodents the effects of oestrogen on SSN and mechanical changes following immobilization and re‐ambulation are unknown. Here we investigated the effects of oestrogen deficiency (i.e., ovariectomized; OVX model) on SSN loss, recovery and contractile function following hindlimb immobilization and 4 weeks of voluntary ambulation. In female Sprague–Dawley rats [(Intact; high oestrogen; n = 24; mass = 290.6 g ± 25.1 g), (OVX; low oestrogen; n = 24; mass = 317.8 g ± 27.3 g)], each left hind‐limb was immobilized in maximal plantar flexion (shortened muscle position) for 14 days. In vivo plantar flexor torque and power were assessed pre‐cast and at 0, 1, 2 and 4 weeks post‐cast. Six rats per group were euthanized at each post‐cast time point for measurements of soleus and medial gastrocnemius SSN. Immediately post‐cast, soleus and medial gastrocnemius SSN and plantar flexor peak torque were reduced similarly in both groups (∼16% and ∼45%, respectively; P < 0.05). After 4 weeks of re‐ambulation, intact rats demonstrated full recovery of SSN and torque, whereas OVX rats exhibited persistent deficits (−10% and −30%, respectively; P < 0.05). These findings indicate that oestrogen facilitates serial sarcomerogenesis and functional recovery following immobilization in female skeletal muscle.
Alex Kirkup, Amelia Rilling, Alexander M. Zero et al.· Experimental Physiology· 0 citations
EMS applied during LPS-induced systemic inflammation exacerbated skeletal muscle atrophy and was associated with activation of IL-6/STAT3-C/EBPδ signaling and proteolytic pathways.
Shino Matsukawa, Shinichi Kai, Hideya Seo et al.· Anesthesia and Analgesia· 0 citations
Background Skeletal muscle changes following stroke are a major factor influencing subsequent motor recovery. Objective To examine the effects of early low-intensity exercise on motor function, neurological deficits, soleus muscle mass, fiber-type composition, and muscle fiber cross-sectional area following experimental stroke. Methods Adult male Wistar rats were randomly assigned to ischemia-control (IC; n = 23) and ischemia-exercise (IE; n = 23) groups. Stroke was induced 90 min after occlusion of the left middle cerebral artery. The next day, the rats ran on a treadmill for 20 min once a day for up to 28 days. The beam-walking test and a neurological evaluation scale were used to assess post-ischemia functional recovery. The muscle fiber characteristics of the soleus of both sides were examined using histochemical and morphometric methods at 1, 3, 5, 7, 14, and 28 days post-stroke. Results Compared to that in the IC group, the motor recovery and neurological function on day 28 were significantly greater in the IE group. The infarct volumes were initially comparable; however, the IE group exhibited a significant reduction beginning on day 5, and two-way ANOVA confirmed smaller infarct volumes in the IE group overall. The soleus muscle weight, fiber-type distribution, and cross-sectional area showed no significant temporal or between-group differences. Conclusions Early exercise intervention promotes functional recovery and may attenuate lesion progression as assessed by TTC staining without detectable deterioration of soleus muscle morphology, highlighting the potential value of safe early mobilization after stroke.
F. Matsuda· Frontiers in Rehabilitation...· 0 citations
