The Regulation of Differentiation of Mesenchymal Stem-cells into Skeletal Muscle: A Look at Signalling Molecules Involved in Myogenesis.

Mesenchymal Stem Cells (MSCs) are an attractive option for the development of treatment for musculoskeletal pathologies due to their wide availability, clinical safety and multiple techniques available. Understanding the control of MSC differentiation into skeletal muscle is vital for developing protocols and therapeutic applications that are safe and effective. This paper therefore aims to review the current understanding of factors that regulate the differentiation of MSCs into skeletal muscle. Medline, Embase, Pubmed and Web of Science were searched for December 2015 using the terms 'differentia*, skeletal*, skeleton*, myocyt*, myogen* and mesenchym* stem-cell*. This returned a total of 1215 results. 48 papers were included in the review. Forty-eight studies were reviewed. Eight related to external signalling molecules, sixteen related to local environmental factors and twenty-four related to intracellular signalling pathways. Uniaxial strain, medium stiffness of the extracellular matrix and submicron grooved topography were identified as promoting myogenesis. TGF-ß was identified as a main inhibitor of myogenesis. Smad and Pax signalling were identified as important intracellular pathways and the relationship of menin, Setdb1, GEFT, PAX3-FOXO1, IGF-II, TAZ and PRDM2 with MyoD and MyoG was explored. Further research into the effect of the inflammatory response on skeletal muscle differentiation is suggested. Clarification of the mechanism of action of TGF-ß, the role of submicron grooves and cyclic uniaxial strain, and two important factors in the development of tissue scaffolds.

A systematic review of dynamometry and its role in hand trauma assessment.

The dynamometer was developed by American neurologists and came into general use in the late 19th century. It is still used in various ways as a diagnostic and prognostic tool in clinical settings. In this systematic review we assessed in detail the different uses of dynamometry, its reliability, different dynamometers used and the influence of rater experience by bringing together and evaluating all published literature in this field. It was found that dynamometry is applied in a wide range of medical conditions. Furthermore, the great majority of studies reported acceptable to high reliability of dynamometry. Jamar mechanical dynamometer was used most often in the studies reviewed. There were mixed results concerning the effect of rater experience. The factors influencing the results of dynamometry were identified as age, gender, body weight, grip strength, BMI, non/dominant hand, assessing upper/lower limbs, rater and patient's strength and the distance from the joint where the dynamometer is placed. This review provides an understanding of the relevance and significance of dynamometry which should serve as a starting point to guide its use in hand trauma assessment. On the basis of our findings, we suggest that hand dynamometry has a great potential, and could be used more often in clinical practice.

Advances of peripheral nerve repair techniques to improve hand function: a systematic review of literature.

Concepts of neuronal damage and repair date back to ancient times. The research in this topic has been growing ever since and numerous nerve repair techniques have evolved throughout the years. Due to our greater understanding of nerve injuries and repair we now distinguish between central and peripheral nervous system. In this review, we have chosen to concentrate on peripheral nerve injuries and in particular those involving the hand. There are no reviews bringing together and summarizing the latest research evidence concerning the most up-to-date techniques used to improve hand function. Therefore, by identifying and evaluating all the published literature in this field, we have summarized all the available information about the advances in peripheral nerve techniques used to improve hand function. The most important ones are the use of resorbable poly[(R)-3-hydroxybutyrate] (PHB), epineural end-to-end suturing, graft repair, nerve transfer, side to side neurorrhaphy and end to side neurorrhaphy between median, radial and ulnar nerves, nerve transplant, nerve repair, external neurolysis and epineural sutures, adjacent neurotization without nerve suturing, Agee endoscopic operation, tourniquet induced anesthesia, toe transfer and meticulous intrinsic repair, free auto nerve grafting, use of distal based neurocutaneous flaps and tubulization. At the same time we found that the patient's age, tension of repair, time of repair, level of injury and scar formation following surgery affect the prognosis. Despite the thorough findings of this systematic review we suggest that further research in this field is needed.

Sources of adult mesenchymal stem cells applicable for musculoskeletal applications - a systematic review of the literature.

Mesenchymal stem cells (MSCs) were first discovered by Friedenstein and his colleagues in 1976 from bone marrow. The unique property of these cells was their potential to develop into fibroblastic colony forming cells. Since Friedenstein's discovery of these cells the interest in adult MSCs has been progressively growing. Nowadays MSCs are defined as undeveloped biological cells capable of proliferation, self renewal and regenerating tissues. All these properties of MSCs have been discovered in the past 35 years. MSCs can play a crucial role in tissue engineering, organogenesis, gene therapy, transplants as well as tissue injuries. These cells were mainly extracted from bone marrow but there have been additional sources for MSCs discovered in the laboratories including: muscle, dermis, trabecular bone, adipose tissue, periosteum, pericyte, blood, synovial membrane and so forth. The discovery of the alternative sources of MSCs helps widen the application of these cells in different areas of medicine. By way of illustration, they can be used in various therapeutic purposes such as tissue regeneration and repair in musculoskeletal diseases including osteonecrosis of femoral head, stimulating growth in children with osteogenesis imperfecta, disc regeneration, osteoarthritis and duchenne muscular dystrophy. In order to fully comprehend the characteristics and potential of MSCs future studies in this field are essential.

Molecular determinants of U-type inactivation in Kv2.1 channels.

Kv2.1 channels exhibit a U-shaped voltage-dependence of inactivation that is thought to represent preferential inactivation from preopen closed states. However, the molecular mechanisms underlying so-called U-type inactivation are unknown. We have performed a cysteine scan of the S3-S4 and S5-P-loop linkers and found sites that are important for U-type inactivation. In the S5-P-loop linker, U-type inactivation was preserved in all mutant channels except E352C. This mutation, but not E352Q, abolished closed-state inactivation while preserving open-state inactivation, resulting in a loss of the U-shaped voltage profile. The reducing agent DTT, as well as the C232V mutation in S2, restored U-type inactivation to the E352C mutant, which suggests that residues 352C and C232 may interact to prevent U-type inactivation. The R289C mutation, in the S3-S4 linker, also reduced U-type inactivation. In this case, DTT had little effect but application of MTSET restored wild-type-like U-type inactivation behavior, suggestive of the importance of charge at this site. Kinetic modeling suggests that the E352C and R289C inactivation phenotypes largely resulted from reductions in the rate constants for transitions from closed to inactivated states. The data indicate that specific residues within the S3-S4 and S5-P-loop linkers may play important roles in Kv2.1 U-type inactivation.

Dynactin regulates bidirectional transport of dense-core vesicles in the axon and dendrites of cultured hippocampal neurons.

A critical aspect of nerve cell function is peptidergic secretion involving the packaging, transport, and processing of a large group of peptide hormones and other signaling molecules, e.g. brain-derived neurotrophic factor (BDNF). Dense-core vesicles (DCVs) are the organelles that transport these molecules to release sites in both the axon and dendrites of pyramidal neurons. DCVs exhibit complex transport behavior, where these organelles move bidirectionally, reverse direction, pause intermittently, and vary in velocities and run lengths. A key objective in the field of organelle transport is to define the molecules that mediate transport. This study investigated the role of dynactin, a putative opposite-polarity motor coordinator, in the microtubule-based transport of DCVs in primary cultured hippocampal neurons. First, by live cell imaging, we showed similar microtubule-based transport of BDNF, neuropeptide Y (NPY), and tissue plasminogen activator (tPA), consistent with the co-packaging of these DCV cargoes. However, we found higher DCV velocities in both the axon and dendrites than those of previous neuronal studies likely due to faster image acquisition times. Then, using well-characterized dynactin disruptors we demonstrate the need for dynactin in bidirectional transport where overexpression of both p50/dynamitin and the first coiled-coil domain of p150(Glued) (CC1) reduces the flux of DCVs in both directions in the axon and dendrites. We also observed that only CC1 reduces axonal and dendritic run lengths. These results suggest different functions for p50 and p150 in the dynactin complex in DCV transport. These findings are significant because they demonstrate that dynactin functions as a motor coordinator for the transport of DCVs in primary cultured rat hippocampal neurons.

Super-thin abdominal skin pedicle flap for the reconstruction of hypertrophic and contracted dorsal hand burn scars.

Dorsal contracture is one of the most common complications of burned hand and can result in a spectrum of deformities and functional disabilities. The injury usually necessitates surgical reconstruction and to the majority of patients, cosmetic end result is a very important issue. In this retrospective study, the authors present the technique of super-thin skin abdominal pedicle flap for the treatment of dorsal hand hypertrophic burn contracture, and review the results. Overall 42 medium or large hypertrophic and contracted scars of the dorsal hand in 34 patients were treated using this procedure. Generally, the functional and aesthetic outcomes were evaluated as good. The functional results were comparable to employment of other types of flap with no relapse of contracture. From the aesthetic point of view, the reconstructed skin was similar to the skin of the rest of the extremity, with good color match, bulkiness, laxity, and suppleness. The scar of the donor region was comparable to the scar of abdominoplasty procedures on the ipsi-lateral side of the lower abdomen. Therefore, this procedure can be considered a reliable and technically simple modality in the treatment of dorsal hand burn contractures.