The role of epimysium in suturing skeletal muscle lacerations

Exploring the role of natural bioactive molecules in genitourinary cancers: how far has research progressed?

The primary approaches to treat cancerous diseases include drug treatment, surgical procedures, biotherapy, and radiation therapy. Chemotherapy has been the primary treatment for cancer for a long time, but its main drawback is that it kills cancerous cells along with healthy ones, leading to deadly adverse health effects. However, genitourinary cancer has become a concern in recent years as it is more common in middle-aged people. So, researchers are trying to find possible therapeutic options from natural small molecules due to the many drawbacks associated with chemotherapy and other radiation-based therapies. Plenty of research was conducted regarding genitourinary cancer to determine the promising role of natural small molecules. So, this review focused on natural small molecules along with their potential therapeutic targets in the case of genitourinary cancers such as prostate cancer, renal cancer, bladder cancer, testicular cancer, and so on. Also, this review states some ongoing or completed clinical evidence in this regard.

Skeletal muscle: Modeling the mechanical behavior by taking the hierarchical microstructure into account

Skeletal muscles ensure the mobility of mammals and are complex natural fiber-matrix-composites with a hierarchical microstructure. In this work, we analyze the muscle's mechanical behavior on the level of fascicles and muscle fibers. We introduce continuum mechanics hyperelastic material models for the connective tissue endomysium and the embedded muscle fibers. The coupled electrical, chemical and mechanical processes taking place in activated contracting muscle fibers are captured including the temporal change of the activation level and the spatial propagation of the activation potential in fibers. In our model, we investigate the material behavior of fascicle, fiber and endomysium in the fiber direction and examine interactions between muscle fiber and endomysium by considering the temporal and spatial change of muscle fiber activation. In addition, a loading case of normal and shear forces is applied to analyze the fiber lifting force and the lifting height of unipennate muscles with different pennation angles. Moreover, the development of local stresses and strains in fibers and endomysium for different strains are studied. The simulation results allow to identify regions in high risk of damage. Optimal arrangements of unipennate muscle microstructure are found for either very small or very large pennation angles.

Reconstitution of the complete rupture in musculotendinous junction using skeletal muscle-derived multipotent stem cell sheet-pellets as a "bio-bond"

Background. Significant and/or complete rupture in the musculotendinous junction (MTJ) is a challenging lesion to treat because of the lack of reliable suture methods. Skeletal muscle-derived multipotent stem cell (Sk-MSC) sheet-pellets, which are able to reconstitute peripheral nerve and muscular/vascular tissues with robust connective tissue networks, have been applied as a “bio-bond”.

Methods. Sk-MSC sheet-pellets, derived from GFP transgenic-mice after 7 days of expansion culture, were detached with EDTA to maintain cell–cell connections. A completely ruptured MTJ model was prepared in the right tibialis anterior (TA) of the recipient mice, and was covered with sheet-pellets. The left side was preserved as a contralateral control. The control group received the same amount of the cell-free medium. The sheet-pellet transplantation (SP) group was further divided into two groups; as the short term (4–8 weeks) and long term (14–18 weeks) recovery group. At each time point after transplantation, tetanic tension output was measured through the electrical stimulation of the sciatic nerve. The behavior of engrafted GFP⁺ tissues and cells was analyzed by fluorescence immunohistochemistry.

Results. The SP short term recovery group showed average 64% recovery of muscle mass, and 36% recovery of tetanic tension output relative to the contralateral side. Then, the SP long term recovery group showed increased recovery of average muscle mass (77%) and tetanic tension output (49%). However, the control group showed no recovery of continuity between muscle and tendon, and demonstrated increased muscle atrophy, with coalescence to the tibia during 4–8 weeks after operation. Histological evidence also supported the above functional recovery of SP group. Engrafted Sk-MSCs primarily formed the connective tissues and muscle fibers, including nerve-vascular networks, and bridged the ruptured tendon–muscle fiber units, with differentiation into skeletal muscle cells, Schwann cells, vascular smooth muscle, and endothelial cells.

Discussion. This bridging capacity between tendon and muscle fibers of the Sk-MSC sheet-pellet, as a “bio-bond,” represents a possible treatment for various MTJ ruptures following surgery.

Muscle injury: review of experimental models

Skeletal muscle is the most abundant tissue in the human body. Its main characteristic is the capacity to regenerate after injury independent of the cause of injury through a process called inflammatory response. Mechanical injuries are the most common type of the skeletal muscle injuries and are classified into one of three areas strain, contusion, and laceration. First, this review aims to describe and compare the main experimental methods that replicate the mechanical muscle injuries. There are several ways to replicate each kind of mechanical injury; there are, however, specific characteristics that must be taken into account when choosing the most appropriate model for the experiment. Finally, this review discusses the context of mechanical injury considering types, variability of methods, and the ability to reproduce injury models.

Anatomic guide and sonography for surgical repair of leg muscle lacerations

BACKGROUND

There were over 110,000 leg laceration cases reported in the United States in 2011. Currently, muscle laceration is repaired by suturing epimysium to epimysium. Tendon-to-tendon repair is stronger, restores the muscle's resting length, and leads to a better functional recovery. Tendons retract into the muscle belly following laceration and surgeons have a difficult time finding them. Many surgeons are unfamiliar with leg muscle anatomy and the fact that the leg muscles have long intramuscular tendons that are not visible in situ. A surgical anatomic guide exists to help surgeons locate forearm tendons; no such guide exists for tendons in the leg.

MATERIALS AND METHODS

The leg tendon ends of 11 cadavers were dissected, measured, and recorded as percentages of leg length. High-frequency ultrasound was used to locate tendon ends in three additional cadavers. These locations were compared with the actual tendon ends located via dissection.

RESULTS

There was little variation in tendon end position within the cadaver group, between men and women or right and left legs. The data are presented as an anatomic guide to inform surgeons of the tendon ends' likely locations in the leg.

CONCLUSION

The location of leg intramuscular tendon ends is predictable and the anatomic guide will help surgeons locate tendon ends and perform tendon-to-tendon repairs. Ultrasound is a potentially effective tool for detection of accurate location of repairable tendon ends in leg muscle lacerations.

The role of intramuscular nerve repair in the recovery of lacerated skeletal muscles

The repair of lacerated muscle often results in suboptimal recovery. An important cause of poor outcome is denervation of the distal segment. The rabbit medial gastrocnemius muscle laceration model was used to assess whether intramuscular nerve repair resulted in better recovery. Lacerated rabbit muscles were divided into three groups: group A had no muscle repair; group B underwent muscle repair; and group C had muscle repair with intramuscular nerve repair. At 7 months, groups A and B showed significantly greater muscle atrophy, replacement of muscle fiber with scar and adipose tissue, and change of muscle fiber type from a fast-twitch to a slow-twitch pattern compared to group C. A clinical case study subsequently demonstrated feasibility of intramuscular nerve repair; reinnervation of the distal belly led to rapid functional recovery. In conclusion, primary intramuscular nerve repair results in better functional outcomes following repair of lacerated muscles.