Polypropylene mesh inhibits post-laminectomy compressive scar formation in rabbits: Histopathological and computational morphometric evaluation.

We evaluated the effect of polypropylene mesh placement on post-laminectomy compressive scar formation in rabbits. Twenty-two white male New Zealand rabbits were distributed into two groups (n = 11). In the control group, the animals underwent lumbosacral laminectomy, whereas in the mesh group, the rabbits were submitted to lumbosacral laminectomy followed by the attachment of a polypropylene mesh to the vertebrae by the application of N-butyl cyanoacrylate. After eight weeks, the rabbits were euthanized, and the laminectomy area was collected for macro- and microscopic analyses. Macroscopically, we evaluated the (1) vertebral canal height; (2) laminectomy width and (3) length; and (4) fibrosis width, (5) height, and (6) length. Microscopically, we evaluated (7) fibroblasts; (8) the thickness of the dura-mater; and (9) the distance between the dura-mater and the laminectomy area. Macroscopically, there were no differences between the groups regarding vertebral canal height; width and length of the laminectomy; and fibrosis width. However, the height, and length of fibrosis were smaller in the mesh group. Microscopically, there were no differences in dura mater thickness and the distance between the dura mater and laminectomy area, but fewer fibroblasts were observed in the mesh group. This indicated that the polypropylene mesh improved tissue repair, with greater tissue organization. The results demonstrate that the use of a polypropylene mesh in the treatment of post-laminectomy wounds in rabbits reduces the severity of compressive fibrous scar formation. Polypropylene mesh is presented as a good alternative to reduce complications associated with laminectomy surgeries.

Morphometric and Molecular Muscle Remodeling after Passive Stretching in Elderly Female Rats.

OBJECTIVES: To determine the effects of three sessions of a passive stretching exercise protocol on the muscles of elderly female rats. METHODS: The effects of the stretching exercises on the soleus muscle were analyzed using immunohistochemistry [tissue inhibitors of matrix metalloproteinases (TIMP), the tumor necrosis factor-alpha (TNF-α), and the gene expression levels using real-time PCR of the transforming growth factor-beta 1 (TGF-ß1), collagen type 1 (COL1), and collagen type 3 (COL3)]. Fifteen 26-month-old female Wistar rats were randomly divided into two groups, namely, Stretching (SG, n=8) and Control (CG, n=7). The passive mechanical stretching protocol consisted of a set of 4 1-minute repetitions, with 30 seconds between each repetition (total treatment of 4 minutes), three times a week for 1 week. RESULTS: Immunohistochemical analysis revealed an increase of 71.4% in the TNF-α (p=0.04) gene expression levels for the SG and a 58% decrease in the TGF-ß1 gene expression levels (p=0.005) in the SG compared to that in the CG. No significant differences were observed between the groups for the immunostaining of TIMP-1 or the gene expression levels of COL1 and COL3. CONCLUSION: Three sessions of static stretching reduced the gene expression level of TGF-ß1, which, owing to its anti-fibrotic role, might contribute to the remodeling of the intramuscular connective tissue of the aging muscle. In addition, immunostaining revealed that TNF-α levels increased in the aging muscle tissue in response to stretching, indicating its effect on stimulating extracellular matrix degradation. These outcomes have important clinical implications in reinforcing the use of stretching exercises in the elderly, considering that the aging muscle presents an infiltration of connective tissue.

Effects of chronic stretching on soleus muscle of Wistar female rats / Efectos del estiramiento crónico en el músculo sóleo de ratas hembras Wistar

The purpose of this study was to evaluate the chronic effects of stretching exercise on soleus muscle histomorphology and histomorphometry of young and aged rats. Thirty-eight female rats were divided into young control group (YCG, n=10;274±50 g); young stretching group (YSG, n=8;274±12 g); aged control group (ACG, n=10;335±39 g); and aged stretching group (ASG, n=10;321±32g). A mechanical apparatus was used to stretch muscle in 4 repetitions, 60 s each, 30 s interval between repetitions in each session, 3 times a week for 3 weeks. Twenty-four hours after the last stretching session, soleus muscle was removed for micromorphology and immunostaining analysis. Data analyses were performed with one-way ANOVA, post-hoc Tukey, or Kruskal-Wallis tests for parametric and nonparametric, respectively (p≤0.05). Muscle fiber cross-sectional area (MFCSA) of ACG was lower (18 %) compared to the YCG. Stretching increased MFCSA comparing YSG to YCG (5,681.15± 1,943.61 µm2 vs 5,119.84±1,857.73 µm2, p=0.00), but decreased comparing ASG to ACG (3,919.54± 1,694.65 µm2 vs 4,172.82±1,446.08 µm2, p=0.00). More serial sarcomere numbers were found in the YSG than YCG (12,062.91±1,564.68 vs 10,070.39±1,072.38, p=0.03). Collagen I and collagen III were higher in YSG than ASG (7.44±7.18 % vs 0.07±0.09 %, p=0.04) and (14.37 %± 9.54 % vs 5.51 %±5.52 %, p=0.00), respectively. TNF-a was greater in ASG than YSG (43.42 %±40.19 % vs 1.72 ± 2.02 %, p=0.00). Epimysium was larger in the YSG compared to YCG (201.83±132.07 % vs 181.09±147.04 %, p=0.00). After 3-week stretching the soleus muscles from aged rats were smaller than their younger counter-parts. Interestingly, while stretching appeared to positively affect young soleus muscle, the opposite was detected in the muscle of the aged rats.

El propósito de este estudio fue evaluar los efectos crónicos del ejercicio de estiramiento sobre la histomorfología e histomorfometría del músculo sóleo de ratas jóvenes y envejecidas. Se dividieron 38 ratas hembras en un grupo control joven (YCG, n = 10; 274 ± 50 g); grupo de estiramiento joven (YSG, n = 8; 274 ± 12 g); grupo control de edad (ACG, n = 10; 335 ± 39 g); y grupo estiramiento envejecido (ASG, n = 10; 321 ± 32 g). Se usó un aparato mecánico para estirar el músculo en 4 repeticiones, 60 s cada una, intervalo de 30 s entre repeticiones en cada sesión, 3 veces por semana, durante 3 semanas. Veinticuatro horas después de la última sesión de estiramiento, se extrajo el músculo sóleo para análisis de micromorfología e inmunotinción. Los análisis de datos se realizaron con pruebas ANOVA de una vía, Tukey post-hoc o Kruskal-Wallis para pruebas paramétricas y no paramétricas, respectivamente (p≤0,05). El área de la sección transversal de fibra muscular (MFCSA) de GCE fue menor (18 %) en comparación con el GCJ. El estiramiento aumentó ASTFM comparando GEJ con GCJ (5.681,15 ± 1.943,61 µm2 vs 5.119,84 ± 1.857,73 µm2, p = 0,00), pero disminuyó comparando GEE con GCE (3.919,54 ± 1.694,65 µm2 vs 4.172,82 ± 1.446,08 µm2, p = 0,00). Se encontraron más sarcómeros en serie en el GEJ que en el GCJ (12.062,91 ± 1.564,68 vs 10.070,39 ± 1,072.38, p = 0,03). El colágeno I y el colágeno III fueron más numerosos en GEJ que en GEE (7,44 ± 7.18 % vs 0,07 ± 0,09 %, p = 0,04) y (14,37 % ± 9,54 % vs 5,51 % ± 5,52 %, p = 0,00), respectivamente. TNF-α fue mayor en GEE que GEJ (43,42 % ± 40,19 % vs 1,72 ± 2,02 %, p = 0,00). El epimisio fue mayor en el GEJ en comparación con el GCJ (201,83 ± 132,07 % vs 181,09 ± 147,04 %, p = 0,00). Después de 3 semanas de estiramiento, los músculos sóleo de las ratas envejecidas eran más pequeños que sus contrapartes más jóvenes. Curiosamente, si bien el estiramiento pareció afectar positivamente el músculo sóleo joven, se detectó lo contrario en el músculo de las ratas envejecidas.

Morphometric and molecular muscle remodeling after passive stretching in elderly female rats

OBJECTIVES: To determine the effects of three sessions of a passive stretching exercise protocol on the muscles of elderly female rats. METHODS: The effects of the stretching exercises on the soleus muscle were analyzed using immunohistochemistry [tissue inhibitors of matrix metalloproteinases (TIMP), the tumor necrosis factor-alpha (TNF-α), and the gene expression levels using real-time PCR of the transforming growth factor-beta 1 (TGF-β1), collagen type 1 (COL1), and collagen type 3 (COL3)]. Fifteen 26-month-old female Wistar rats were randomly divided into two groups, namely, Stretching (SG, n=8) and Control (CG, n=7). The passive mechanical stretching protocol consisted of a set of 4 1-minute repetitions, with 30 seconds between each repetition (total treatment of 4 minutes), three times a week for 1 week. RESULTS: Immunohistochemical analysis revealed an increase of 71.4% in the TNF-α (p=0.04) gene expression levels for the SG and a 58% decrease in the TGF-β1 gene expression levels (p=0.005) in the SG compared to that in the CG. No significant differences were observed between the groups for the immunostaining of TIMP-1 or the gene expression levels of COL1 and COL3. CONCLUSION: Three sessions of static stretching reduced the gene expression level of TGF-β1, which, owing to its anti-fibrotic role, might contribute to the remodeling of the intramuscular connective tissue of the aging muscle. In addition, immunostaining revealed that TNF-α levels increased in the aging muscle tissue in response to stretching, indicating its effect on stimulating extracellular matrix degradation. These outcomes have important clinical implications in reinforcing the use of stretching exercises in the elderly, considering that the aging muscle presents an infiltration of connective tissue.

Systemic Infusion of Expanded CD133+ Cells and Expanded CD133+ Cell-Derived EVs for the Treatment of Ischemic Cardiomyopathy in a Rat Model of AMI.

Myocardial infarction is a leading cause of death among all cardiovascular diseases. Cell therapies using a cell population enriched with endothelial progenitor cells (EPCs), expanded CD133+ cells, have promise as a therapeutic option for the treatment of ischemic areas after infarction. Recently, secreted membrane vesicles, including exosomes and microvesicles, have been recognized as new therapeutic candidates with important roles in intercellular and tissue communication. Expanded CD133+ cells have the ability to produce extracellular vesicles (EVs); however, their effect in the context of the heart is unknown. In the present study, we evaluated the effectiveness of the systemic application of expanded CD133+ cells and expanded CD133+ cell-derived EVs for the treatment of ischemic cardiomyopathy in a rat model of acute myocardial infarction (AMI) and examined the hypothesis that the EVs, because of their critical role in transferring regenerative signals from stem cells to the injured tissues, might elicit an equal or better therapeutic response than the expanded CD133+ cells. We demonstrate that the systemic application of expanded CD133+ cells and EVs has similar effects in infarcted rats. Few animals per group showed improvements in several heart and kidney parameters analyzed, but not significant differences were observed when comparing the groups. The systemic route may not be effective to treat ischemic cardiomyopathy; nonetheless, it may be a beneficial therapy to treat the side effects of AMI such as kidney damage.

Acute effects of stretching exercise on the soleus muscle of female aged rats.

UNLABELLED: It has been shown that stretching exercises can improve the flexibility and independence of the elderly. However, although these exercises commonly constitute training programs, the morphological adaptations induced by stretching exercises in aged skeletal muscle are still unclear. OBJECTIVE: To assess the acute effects of passive mechanical static stretching on the morphology, sarcomerogenesis and modulation of important components of the extracellular matrix of the soleus muscle of aged female rats. METHODS: Fifteen old female rats with 26 months were divided into two groups: stretching (n=8, SG) and control (n=7, CG): The stretching protocol consisted of 4 repetitions each of 1 min with 30s interval between sets. Stretching was performed on the left soleus muscle, 3 times a week for 1 week. After three sessions, the rats were anesthetized to remove the left soleus muscle, and then euthanized. The following analyses were carried out: muscle fiber cross-sectional area and serial sarcomere number; immunohistochemistry for the quantification of collagen I, III and TGFß-1. RESULTS: a decrease in muscle fiber cross-sectional area of the SG was observed when compared to the CG (p=0.0001, Kruskal-Wallis); the percentage of type I collagen was significantly lower in the SG when compared to the CG (p=0.01, Kruskal-Wallis), as well as the percentage of TGFß-1 (p=0.04, Kruskal-Wallis); collagen III was significantly higher in the SG than in the CG (7.06±6.88% vs 4.92±5.30%, p=0.01, Kruskal-Wallis). CONCLUSION: Although the acute stretching induced muscle hypotrophy, an antifibrotic action was detected.

Direct intracardiac injection of umbilical cord-derived stromal cells and umbilical cord blood-derived endothelial cells for the treatment of ischemic cardiomyopathy.

The development of new therapeutic strategies is necessary to reduce the worldwide social and economic impact of cardiovascular disease, which produces high rates of morbidity and mortality. A therapeutic option that has emerged in the last decade is cell therapy. The aim of this study was to compare the effect of transplanting human umbilical cord-derived stromal cells (UCSCs), human umbilical cord blood-derived endothelial cells (UCBECs) or a combination of these two cell types for the treatment of ischemic cardiomyopathy (IC) in a Wistar rat model. IC was induced by left coronary artery ligation, and baseline echocardiography was performed seven days later. Animals with a left ventricular ejection fraction (LVEF) of ≤40% were selected for the study. On the ninth day after IC was induced, the animals were randomized into the following experimental groups: UCSCs, UCBECs, UCSCs plus UCBECs, or vehicle (control). Thirty days after treatment, an echocardiographic analysis was performed, followed by euthanasia. The animals in all of the cell therapy groups, regardless of the cell type transplanted, had less collagen deposition in their heart tissue and demonstrated a significant improvement in myocardial function after IC. Furthermore, there was a trend of increasing numbers of blood vessels in the infarcted area. The median value of LVEF increased by 7.19% to 11.77%, whereas the control group decreased by 0.24%. These results suggest that UCSCs and UCBECs are promising cells for cellular cardiomyoplasty and can be an effective therapy for improving cardiac function following IC.