Myostatin deficiency is associated with an increase in number of total axons and motor axons innervating mouse tibialis anterior muscle.

Introduction: Myostatin (Mstn) is a secreted protein that acts as a negative regulator of skeletal muscle mass. However, a critical evaluation of neuromuscular aspects of hypertrophied muscles induced by Mstn deficiency has not been done.

Methods: We compared the tibialis anterior muscle-nerve interrelationships in wild-type and Mstn-null mice of both genders by immunohistochemical analyses, which allowed us to count the number of total axons and motor axons and estimate the size of motor units and the innervation ratio of the tibialis anterior muscle (TAm).

Wnt4 activates the canonical β-catenin pathway and regulates negatively myostatin: functional implication in myogenesis.

Expression of Wnt proteins is known to be important for developmental processes such as embryonic pattern formation and determination of cell fate. Previous studies have shown that Wn4 was involved in the myogenic fate of somites, in the myogenic proliferation, and differentiation of skeletal muscle. However, the function of this factor in adult muscle homeostasis remains not well understood.

Aldehyde dehydrogenase activity promotes survival of human muscle precursor cells.

Aldehyde dehydrogenases (ALDH) are a family of enzymes that efficiently detoxify aldehydic products generated by reactive oxygen species and might therefore participate in cell survival. Because ALDH activity has been used to identify normal and malignant cells with stem cell properties, we asked whether human myogenic precursor cells (myoblasts) could be identified and isolated based on their levels of ALDH activity. Human muscle explant-derived cells were incubated with ALDEFLUOR, a fluorescent substrate for ALDH, and we determined by flow cytometry the level of enzyme activity.

Inhibition of myoblast differentiation by Sfrp1 and Sfrp2.

Secreted Frizzled-related proteins (Sfrps) are extracellular regulators of Wnt signalling and play important roles in developmental and oncogenic processes. They are known to be upregulated in regenerating muscle and in myoblast cultures but their function is unknown. Here, we show that the addition of recombinant Sfrp1 or Sfrp2 to C2C12 cell line cultures or to primary cultures of satellite cells results in the inhibition of myotube formation with no significant effect on the cell cycle or apoptosis.

Transplantation of adult myoblasts or adipose tissue precursor cells by high-density injection failed to improve reinnervated skeletal muscles.

We previously showed that transfer of adult myoblasts (MB) into cardiotoxin-damaged muscle improved the properties of reinnervated tibialis anterior muscle of rabbits. However, this cell therapy protocol cannot be applied to humans because of the hazardous effects of the myotoxin. To circumvent this approach, we used the recently developed high-density injection technique to autotransplant cultured cells 1 mm from each other into the tibialis anterior muscle without previous cardiotoxin-induced damage.

Short- or long-term effects of adult myoblast transfer on properties of reinnervated skeletal muscles.

Skeletal muscle demonstrates a force deficit after repair of injured peripheral nerves. Data from the literature indicate that myoblast transfer enhances recovery of muscle function. Thus, we tested the hypothesis that transfer of adult myoblasts improves the properties of reinnervated rabbit tibialis anterior (TA) muscles in both the short term (4 months) and long term (14 months).

Transplantation of adipose tissue-derived stromal cells increases mass and functional capacity of damaged skeletal muscle.

The regenerating skeletal muscle environment is capable of inducing uncommitted progenitors to terminally differentiate. The aim of this work was to determine whether adipose tissue-derived stromal cells were able to participate in muscle regeneration and to characterize the effect on muscle mass and functional capacities after transplantation of these cells. Adipose tissue stromal cells labeled with Adv cyto LacZ from 3-day-old primary cultures (SVF1) were autotransplanted into damaged tibialis anterior muscles.

Transplantation of Adipose Tissue-Derived Stromal Cells Increases Mass and Functional Capacity of Damaged Skeletal Muscle.

The regenerating skeletal muscle environment is capable of inducing uncommitted progenitors to terminally differentiate. The aim of this work was to determine whether adipose tissue-derived stromal cells were able to participate in muscle regeneration and to characterize the effect on muscle mass and functional capacities after transplantation of these cells. Adipose tissue stromal cells labeled with Adv cyto LacZ from 3-day-old primary cultures (SVF1) were autotransplanted into damaged tibialis anterior muscles.

Transplantation of primary satellite cells improves properties of reinnervated skeletal muscles.

Skeletal muscle demonstrates a force deficit after repair of injured peripheral nerves. We tested the hypothesis that transplantation of satellite cells into reinnervated rabbit tibialis anterior (TA) muscles improves their properties. Adult rabbits underwent transection and immediate suture of the common peroneal nerve.

Preadipocyte conversion to macrophage. Evidence of plasticity.

Preadipocytes are present throughout adult life in adipose tissues and can proliferate and differentiate into mature adipocytes according to the energy balance. An increasing number of reports demonstrate that cells from adipose lineages (preadipocytes and adipocytes) and macrophages share numerous functional or antigenic properties. No large scale comparison reflecting the phenotype complexity has been performed between these different cell types until now.

Changes in mass and performance in rabbit muscles after muscle damage with or without transplantation of primary satellite cells.

Changes in morphology, metabolism, myosin heavy chain gene expression, and functional performances in damaged rabbit muscles with or without transplantation of primary satellite cells were investigated. For this purpose, we damaged bilaterally the fast muscle tibialis anterior (TA) with either 1.5 or 2.

Changes in Mass and Performance in Rabbit Muscles after Muscle Damage with or without Transplantation of Primary Satellite Cells.

Changes in morphology, metabolism, myosin heavy chain gene expression, and functional performances in damaged rabbit muscles with or without transplantation of primary satellite cells were investigated. For this purpose, we damaged bilaterally the fast muscle tibialis anterior (TA) with either 1.5 or 2.