Use of Platelet-Rich Plasma Plus Suramin, an Antifibrotic Agent, to Improve Muscle Healing After Injuries

Chinese Tuina ameliorates muscle damage by regulating endoplasmic reticulum stress and autophagy in a rat model of skeletal muscle contusion

Chinese Tuina has been used to treat skeletal muscle contusion (SMC) for a long time in China, yet its efficacy and mechanisms remain unclear. Previous studies have shown the vital roles of endoplasmic reticulum (ER) stress and autophagy during injured skeletal muscle recovery, we postulated that Chinese Tuina could expedite the healing of SMC by fine-tuning these processes. In this study, we established a rat model of SMC through weight-dropping and divided the rats into three groups: SMC, SMC+Tuina, and SMC+Tuina+ 3-methyladenine (3-MA) groups, while using untreated normal SD rats as a control. We assessed gait and edema via CatWalk gait analysis and swelling measurements, respectively. Tumor necrosis factor-α (TNF-α) expression was determined by immunohistochemistry (IHC). Morphological and ultrastructural alterations in the damaged muscle tissue were examined using hematoxylin and eosin (HE) staining and transmission electron microscopy (TEM), respectively. Expression of GRP78, LC3B and FAM134b was determined by western blot, and Colocalization of LC3B and FAM134b was examined by immunofluorescence. SMC+Tuina exhibited significantly improved gait and reduced edema. SMC+Tuina showed improvements in morphology and ultrastructure of damaged muscles, as well as decreased expression of TNF-α. Additionally, in SMC+Tuina, expression of GRP78 was downregulated, while expressions of FAM134 and LC3B were upregulated, and colocalization of FAM134 and LC3B was also enhanced. However, autophagy inhibitor 3-MA weakened the aforementioned effects of Chinese Tuina. The obtained results indicated that Chinese Tuina has a positive therapeutic effect in rats with SMC, potentially by promoting autophagy to reduce inflammation and ER stress.

The role of platelet-rich plasma in biomedicine: A comprehensive overview

Biomedicine has seen significant advancements in the 21st century, with platelet-rich plasma (PRP) playing a crucial role in clinical practice. This blood derivative, enriched with platelet components, has shown great potential for promoting tissue repair and regeneration. Its wide range of applications and the presence of anti-inflammatory and growth-promoting factors make it a valuable tool in the field of biomedicine. The exploration of PRP in clinical settings has been gaining momentum. Despite its cost-effectiveness, safety, and therapeutic efficacy, the widespread clinical adoption of PRP has been hindered by the absence of consistent preparation standards and standardized treatment protocols. This article provides a comprehensive analysis of the clinical uses, physiological roles, molecular mechanisms, and preparation techniques of PRP in biomedicine. The aim is to offer a thorough understanding of the potential applications and benefits of PRP in medical practice.

Identification of pro-fibrotic cellular subpopulations in fascia of gluteal muscle contracture using single-cell RNA sequencing

Fibrosis is a common and integral pathological feature in various chronic diseases, capable of affecting any tissue or organ. Fibrosis within deep fascia is implicated in many myofascial disorders, including gluteal muscle contracture (GMC), Dupuytren's disease, plantar fasciitis, iliotibial band syndrome, and chronic muscle pain. Despite its clinical significance, deep fascia fibrosis remains considerably under-researched compared to other fibrotic conditions. Single-cell RNA-sequencing (scRNA-seq) has been used to investigate cellular heterogeneity in fibrotic tissues. However, to our knowledge, only a few studies have applied scRNA-seq to explore cellular heterogeneity in deep fascia, and none have specifically examined fibrotic fascia. In this study, we performed scRNA-seq analysis on fibrotic fascia associated with GMC and compared them to nonfibrotic control fascial samples. Our findings show that fibroblast and macrophage cells play critical roles in pathological tissue remodeling within fibrotic deep fascia. We observed an upregulation of various collagens, proteoglycans, and extracellular matrix (ECM) glycoproteins in contracture deep fascia, attributed to the widespread activation of fibroblast subclusters. Additionally, two pro-fibrotic macrophage subpopulations, SPP1+ MP and ECM-like MP, appear to facilitate ECM deposition in fibrotic deep fascia by either regulating fibroblast activation or directly contributing to ECM production. The SPP1+ MP and ECM-like MP cells, as well as the signal interaction between SPP1+ MP and fibroblast cells, present potential therapeutic target for treating GMC and other related myofascial disorders.

Suramin enhances proliferation, migration, and tendon gene expression of human supraspinatus tenocytes

Rotator cuff tendinopathy is a common musculoskeletal disorder with limited pharmacological treatment strategies. This study aimed to investigate tenocytes' functional in vitro response from a ruptured supraspinatus tendon to suramin administration and to elucidate whether suramin can enhance tendon repair and modulate the inflammatory response to injury. Tenocytes were obtained from human supraspinatus tendons (n = 6). We investigated the effect of suramin on LPS-induced inflammatory responses and the underlying molecular mechanisms in THP-1 macrophages. Suramin enhanced the proliferation, cell viability, and migration of tenocytes. It also increased the protein expression of PCNA and Ki-67. Suramin-treated tenocytes exhibited increased expression of COL1A1, COL3A1, TNC, SCX, and VEGF. Suramin significantly reduced LPS-induced iNOS, COX2 synthesis, inflammatory cytokine TNF-α production, and inflammatory signaling by influencing the NF-κB pathways in THP-1 cells. Our results suggest that suramin holds great promise as a therapeutic option for treating rotator cuff tendinopathy.

Platelet-rich plasma does not accelerate the healing of damaged muscle following muscle strain

Although platelet-rich plasma (PRP) has been widely used regardless of the severity of muscle strain, there have been very few basic studies in which its effects on muscle injury were examined by using models that accurately mimic the clinical muscle strain injury process. Therefore, the aim of this study was to confirm by physiological and structural analyses whether PRP purified by a general preparation method has a muscle healing effect on muscle damage caused by eccentric contraction (ECC). Male Wistar rats were subjected to muscle injury induced by ECC in bilateral plantar flexor muscles using electrical stimulation and an automatically dorsiflexing footplate. The rats were randomly assigned to three groups by type of injection: phosphate-buffered saline (PBS), leukocyte-poor PRP (LP-PRP), or leukocyte-rich PRP (LR-PRP) injection into gastrocnemius muscles three times at weekly intervals. The platelet concentrations of the LP-PRP and LR-PRP were three to five times higher than that of whole blood. The recovery process of torque strength in the plantar flexor muscle, signal changes in MRI images, and histological evaluation 3 weeks after injury showed no obvious differences among the three groups, and every muscle recovered well from the injury without marked fibrosis. The results that neither LP-PRP nor LR-PRP was found to accelerate healing of muscle injuries suggested that conventional preparation and use of PRP for simple muscle injuries caused by muscle strain should be carefully considered, and further basic research using models that accurately mimic clinical practice should be carried out to determine the optimal use of PRP.

TGF-β1 stimulation and VDR-dependent activation modulate calcitriol action on skeletal muscle fibroblasts and Smad signalling-associated fibrogenesis

Fibroblasts play a pivotal role in fibrogenesis after skeletal muscle injury. Excess fibrous formation can disrupt contractile functions and delay functional recovery. Although vitamin D receptor (VDR) is expressed explicitly in regenerating muscle compared with uninjured muscle, how calcitriol [1α,25(OH)2D3] directly regulates skeletal muscle primary fibroblast proliferation, the transition to myofibroblasts, and Smad signalling-associated fibrogenesis is currently unknown. Herein, the effects of calcitriol on cultured skeletal muscle primary fibroblasts of male C57BL/6 mice (aged 1 month old) were investigated. The percentage of BrdU+ nuclei in primary fibroblasts was significantly decreased after calcitriol treatment; however, the antiproliferative effect of calcitriol was diminished after TGF-β1 stimulation to induce fibroblast to myofibroblast transition. This suppressive effect was associated with significantly decreased VDR expression in TGF-β1-treated cells. In addition, Vdr siRNA transfection abolished the effects of calcitriol on the suppression of α-SMA expression and Smad2/3 signalling in myofibroblasts, supporting that its antifibrogenic effect requires VDR activation. Compared with calcitriol, the antifibrotic agent suramin could inhibit fibroblast/myofibroblast proliferation and suppress the expression of TCF-4, which regulates fibrogenic determination. Collectively, these findings suggest that profibrotic stimulation and VDR-dependent activation could modulate the effects of calcitriol on skeletal muscle fibroblast proliferation and fibrogenesis processes. Therefore, TGF-β1 and VDR expression levels are crucial determinants for the antifibrogenic effect of calcitriol on skeletal muscle after injury.