Skeletal Muscle Regeneration by the Exosomes of Adipose Tissue-Derived Mesenchymal Stem Cells

Profound skeletal muscle loss can lead to severe disability and cosmetic deformities. Mesenchymal stem cell (MSC)-derived exosomes have shown potential as an effective therapeutic tool for tissue regeneration. This study aimed to determine the regenerative capacity of MSC-derived exosomes for skeletal muscle regeneration. Exosomes were isolated from human adipose tissue-derived MSCs (AD-MSCs). The effects of MSC-derived exosomes on satellite cells were investigated using cell viability, relevant genes, and protein analyses. Moreover, NOD-SCID mice were used and randomly assigned to the healthy control (n = 4), muscle defect (n = 6), and muscle defect + exosome (n = 6) groups. Muscle defects were created using a biopsy punch on the quadriceps of the hind limb. Four weeks after the surgery, the quadriceps muscles were harvested, weighed, and histologically analyzed. MSC-derived exosome treatment increased the proliferation and expression of myocyte-related genes, and immunofluorescence analysis for myogenin revealed a similar trend. Histologically, MSC-derived exosome-treated mice showed relatively preserved shapes and sizes of the muscle bundles. Immunohistochemical staining revealed greater expression of myogenin and myoblast determination protein 1 in the MSC-derived exosome-treated group. These results indicate that exosomes extracted from AD-MSCs have the therapeutic potential for skeletal muscle regeneration.

A Case of Breast Cancer in a Patient with a Congenital Pectoralis Muscle Defect

Congenital pectoral muscle defects are very rare, and when accompanied by limb defects, they are called Poland syndrome. A woman in her 70s, 4 years after partial mastectomy for breast cancer, underwent mastectomy for a local recurrence. During the operation, the pectoralis major and minor muscles were found to be defective. However, the patient did not have any limb defects. Although congenital pectoral muscle defects are very rare, it would be better to confirm defects of the pectoral muscle by preoperative diagnostic imaging such as CT because the postoperative treatment may be affected.

THE ROLE OF PLATELET-RICH FIBRIN FACILITATES THE HEALING OF GASTROCNEMIUS MUSCLE DEFECT: A PRELIMINARY STUDY ON ANIMAL MODEL

Background: Scar formation has been a classical issue in the healing of skeletal muscle defect which will results in decrease of strength and function. Platelet-rich plasma (PRP) has been studied to enhance the healing of muscle defect. The disadvantages of it include the risk of immunologic reaction, time-consuming preparation, and lack of scaffold element. Platelet-rich fibrin (PRF) is a new generation of platelet concentrate that provides good source of growth factors and scaffold element necessary for the healing. This study is to provide a fondation of PRF preparation and implantation for the healing of experimental defect of gastrocnemius muscle in an animal model.Purpose: The goal is to provide a fondation of PRF preparation and implantation for the healing of experimental defect of gastrocnemius muscle in an animal model.Methods: Animal Care and Use Committee, Airlangga University approved the study. Twenty New Zealand white rabbits were divided into two groups. In control group, a defect was created in the right gastrocnemius and no implantation was done. In study group, similar defect was created with implantation of PRF. Two and four weeks after surgery, the defect was examined immunohistochemically for the expression of Pax7 protein.Results: The implanted group showed higher IRS score in two and four weeks compared to the control group.Conclusion: The use of PRF facilitates the healing of muscle injury. This study will be used as a fondation for further study on PRF.

Radiographic Predictors of Elbow Injury and Surgery in Major League Baseball Pitchers

Objectives: To evaluate predictive ability of asymptomatic screening MRI’s of Major League Baseball (MLB) pitchers and compare associated findings with future DL placement, pitching statistics, and elbow surgery. Methods: A total of 40 consecutive asymptomatic elbow MRI’s in MLB pitchers at a single organization were analyzed from 2005 - 2017. Asymptomatic MRI was defined as a screening MRI at time of contract signing having been performed at least 6 months prior to DL placement for any elbow-related injury. Publicly available DL data, career innings pitched, career games started, career pitch count, and career max velocity of pitch were obtained. A blinded investigator examined each MRI for pathological signals. Data was analyzed on players that were eventually placed on the DL compared to those with no DL placement. Results: 40 consecutive elbow MRIs of MLB players were reviewed. The average age of the injured cohort was 28.3 ± 3.2 years (16 players) and 28.8 ± 5.5 years (24 players) for the non-injured cohort. There was no statistical difference in age, handedness, height, weight, or pitching stats between the injured and non-injured cohorts. Abnormal radiographic signal intensity in the UCL (p<0.001) and humeral elevation of the UCL (p=0.01) were significantly associated with future DL placement. Those injured spent an average of 200.7 days and 191.7 days in the DL with signal in the UCL and those with humeral elevation of the UCL, respectively. Ulnar elevation/signal of the UCL (p=0.06), and posteromedial impingement (p=0.08) were approaching statistical significance. Of those injured 68.8% (11/16) underwent elbow surgery. Findings of ligament signal intensity (p<0.001), ulnar-sided UCL elevation (p=0.018), humeral-sided UCL elevation (p=0.002), and posteromedial impingement (p=0.042) were all significantly associated with future surgery. There was no significant correlation between injury and radiocapitellar or ulnohumeral chondral lesion, bone edema, loose bodies, or flexor-pronator mass muscle defect. The presence of a flexor-pronator mass muscle defect was associated with a significantly reduced number of innings pitched (53.7 ± 74.3 vs. 304.4 ± 305.5 innings, p=0.0317), games started (5 ± 7.1 vs. 40.1 ± 49.0 games, p=0.004), and pitch count (680.5 ± 919.9 vs. 40.1 ± 49.0 pitches, p=0.022). The presence of ligament signal (26.2 ± 37.1 vs. 51.7 ± 56.5 games, p=0.036) and ulnar elevation (6.3 ± 9.3 vs. 41.2 ± 9.3 games, p=0.003) was associated with significantly fewer games started. The presence of bone edema was associated with significantly decreased pitch count (1451.2 ± 1746.8 vs. 4128.0 ± 4718.0 pitches, p=0.023). There was no association between humeral UCL elevation, flexor-pronator mass tendon, or posteromedial impingement with innings pitched, games started, or pitch count. Conclusion: The heavy demand placed on the elbow joint in professional pitching produces degenerative changes visible on MRI prior to any symptoms, as demonstrated in previous studies. Specific degenerative changes in the UCL Ligament, particularly humeral sided elevation of the UCL, are significantly associated with future injury. [Table: see text]