Biomaterials and Stem Cell Therapies for Injuries Associated to Skeletal Muscular Tissues - Advances in Biomaterials Science and Biomedical Applications - page 348

generation since these cells produce growth factors, ECM molecules, and even modulate the
inflammatory process.
Figure 4. Undifferentiated MSCs from Wharton's jelly, exhibiting a star-like shape with a flat morphology (100x mag‐
nification).
5. Evaluation of muscle regeneration
Muscle biopsies should be considered in order to obtain careful clinical assessment or for in‐
vestigation purposes. After the collection of the muscle samples, they should be immediate‐
ly equally divided in three. One sample should be placed into formalin (for hematoxilin and
eosin - HE), another sample should be fixed into 2.5% purified glutaraldehyde in 0.1M Sor‐
ensen phosphate buffer (for electron microscopy - EM) and the other sample should remain
unfixed and refrigerated (for histochemistry, biochemistry/genetics analysis).
5.1. Routine histological evaluation
Routine evaluation of the muscle biopsy sample involves the examination of formalin-fixed,
paraffin processed sections and unfixed frozen sections with standard histological and en‐
zyme histochemical stains at the light microscopic level. HE is the routine histological stain
used for evaluation of basic tissue organization and cellular structure. For HE, the whole
piece of tissue should be fixed in a clamp and after the tissue is infiltrated with wax, both
longitudinal and cross sections must be cut before embedding. Five levels should be ob‐
tained, especially in cases suspected of vasculitis. The parameters that can be evaluated are:
the type of inflammatory infiltrate present; examination of the structure of vessels walls
(vasculitis and/or fibrinoid necrosis); presence of endomysial and perimysial fibrosis/fatty