Desmin and Vimentin Expression during Embryonic Development of Tensor Veli Palatini Muscle in Mice

Transcriptomic Profile of Primary Culture of Skeletal Muscle Cells Isolated from Semitendinosus Muscle of Beef and Dairy Bulls

The aim of the study was to identify differences in the transcriptomic profiles of primary muscle cell cultures derived from the semitendinosus muscle of bulls of beef breeds (Limousin (LIM) and Hereford (HER)) and a dairy breed (Holstein-Friesian (HF)) (n = 4 for each breed). Finding a common expression pattern for proliferating cells may point to such an early orientation of the cattle beef phenotype at the transcriptome level of unfused myogenic cells. To check this hypothesis, microarray analyses were performed. The analysis revealed 825 upregulated and 1300 downregulated transcripts similar in both beef breeds (LIM and HER) and significantly different when compared with the dairy breed (HF) used as a reference. Ontological analyses showed that the largest group of genes were involved in muscle organ development. Muscle cells of beef breeds showed higher expression of genes involved in myogenesis (including erbb-3, myf5, myog, des, igf-1, tgfb2) and those encoding proteins comprising the contractile apparatus (acta1, actc1, myh3, myh11, myl1, myl2, myl4, tpm1, tnnt2, tnnc1). The obtained results confirmed our hypothesis that the expression profile of several groups of genes is common in beef breeds at the level of proliferating satellite cells but differs from that observed in typical dairy breeds.

Developmental mechanism of muscle-tendon-bone complex in the fetal soft palate

OBJECTIVE

This study was performed to investigate how the palatine aponeurosis, medial pterygoid process (MPP) of the sphenoid bone, and tensor veli palatini (TVP) muscle form the pulley: muscle-tendon-bone complex.

DESIGN

Mice at embryonic day (ED) 14-17 were used as sample in this study. Azan staining was performed to observe the morphology, and immunohistochemical staining of desmin was performed to closely observe the development of the myotendinous junction. To confirm the bone formation process, immunohistochemical staining of type II collagen (col II), tartrate-resistant acid phosphatase (TRAP), and alkaline phosphatase (ALP) staining were performed. Furthermore, to objectively evaluate bone formation, the major axis and width of the MPP were measured, and osteoclasts that appeared in the MPP were counted.

RESULTS

At ED 14 and 14.5, ALP showed a reaction throughout the MPP. The col II-positive area expanded until ED 16.5, but it was markedly reduced at ED 17. The TVP initially contacted with the palatine aponeurosis at ED 16.5. The major axis and width of the MPP and the number of TRAP-positive osteoclasts were significantly increased as the TVP and palatine aponeurosis joined.

CONCLUSIONS

Therefore, in addition to the tissue units: muscle, tendon, and bone, the interaction in organogenesis promotes rapid growth of the pulley: muscle-tendon-bone complex.

Proliferative activity of skeletal myoblast sheet by paracrine effects of mesenchymal stem cells

OBJECTIVES

The purpose of this study was to examine the proliferative activity enhancement of skeletal myoblasts in the presence and absence of mesenchymal stem cells (MSC).

METHODS

We artificially fabricated two types of cell sheets by co-culturing rabbit skeletal myoblast sheets with rabbit MSCs using type IA collagen gel (MC+), and cell sheets without rabbit MSCs (MC-).

RESULTS

The results of hematoxylin and eosin staining revealed that MC+ was thicker than MC- on day 7. Immunohistochemical staining revealed a low level of desmin expression in both sheets on day 2. Desmin expression increased at days 7 and 12, and desmin localization was consistent with the stratified area. Reverse transcription PCR revealed the presence of MyoD and PAX7 in both sheets on days 2, 7, and 12. The presence of myogenin was confirmed in both sheets on days 7 and 12. Hepatocyte growth factor expression was evident in MC+ on day 2, and in both sheets on day 7. Measurement of cell proliferative activity based on DNA cell cycle analysis indicated that MC+ had significantly higher cell proliferative activity than MC- on day 7. There were no significant differences in cell proliferative activity between MC+ and MC- on day 12.

CONCLUSIONS

This study demonstrated that the presence of MSCs could transiently enhance the proliferative activity of myoblasts, but that this enhancement is ultimately diminished due to contact inhibition.