More resistant tendons obtained from the association of Heteropterys aphrodisiaca and endurance training

Achilles Tendon Repair by Decellularized and Engineered Xenografts in a Rabbit Model

Tendon tissue ruptures often require the replacement of damaged tissues. The use of auto- or allografts is notoriously limited due to the scarce supply and the high risks of immune adverse reactions. To overcome these limitations, tissue engineering (TE) has been considered a promising approach. Among several biomaterials, decellularized xenografts are available in large quantity and could represent a possible solution for tendon reconstruction. The present study is aimed at evaluating TE xenografts in Achilles tendon defects. Specifically, the ability to enhance the biomechanical functionality, while improving the graft interaction with the host, was tested. The combination of decellularized equine-derived tendon xenografts with or without the matrix repopulation with autologous bone marrow mesenchymal stem cells (BMSCs) under stretch-perfusion dynamic conditions might improve the side-to-side tendon reconstruction. Thirty-six New Zealand rabbits were used to create 2 cm long segmental defects of the Achilles tendon. Then, animals were implanted with autograft (AG) as the gold standard control, decellularized graft (DG), or in vitro tissue-engineered graft (TEG) and evaluated postoperatively at 12 weeks. After sacrifice, histological, immunohistochemical, biochemical, and biomechanical analyses were performed along with the matrix metalloproteinases. The results demonstrated the beneficial role of undifferentiated BMSCs loaded within decellularized xenografts undergoing a stretch-perfusion culture as an immunomodulatory weapon reducing the inflammatory process. Interestingly, AG and TEG groups exhibited similar results, behaved similarly, and showed a significant superior tissue healing compared to DG in terms of newly formed collagen fibres and biomechanical parameters. Whereas, DG demonstrated a massive inflammatory and giant cell response associated with graft destruction and necrosis, absence of type I and III collagen, and a higher amount of proteoglycans and MMP-2, thus unfavourably affecting the biomechanical response. In conclusion, this in vivo study suggests a potential use of the proposed tissue-engineered constructs for tendon reconstruction.

De novo generation in an in vivo rat model and biomechanical characterization of autologous transplants for ligament and tendon reconstruction

BACKGROUND

Surgical reconstruction of ligaments and tendons is frequently required in clinical practice. The commonly used autografts, allografts, or synthetic transplants present limitations in terms of availability, biocompatibility, cost, and mechanical properties that tissue bioengineering aims to overcome. It classically combines an exogenous extracellular matrix with cells, but this approach remains complex and expensive. Using a rat model, we tested a new bioengineering strategy for the in vivo and de novo generation of autologous grafts without the addition of extracellular matrix or cells, and analyzed their biomechanical and structural properties.

METHODS

A silicone perforated tubular implant (PTI) was designed and implanted in the spine of male Wistar rats to generate neo-transplants. The tensile load to failure, stiffness, Young modulus, and ultrastructure of the generated tissue were determined at 6 and 12weeks after surgery. The feasibility of using the transplant that was generated in the spine as an autograft for reconstruction of medial collateral ligaments (MCL) and Achilles tendons was also tested.

FINDINGS

Use of the PTI resulted in de novo transplant generation. Their median load to failure and Young modulus increased between 6 and 12weeks (respectively 12N vs 34N and 48MPa vs 178MPa). At 12weeks, the neo-transplants exhibited collagen bundles (mainly type III) parallel to their longitudinal axis and elongated fibroblasts. Six weeks after their transfer to replace the MCL or the Achilles tendon, the transplants were still present, with their ends healed at their insertion point.

INTERPRETATION

This animal study is a first step in the design and validation of a new bioengineering strategy to develop autologous transplants for ligament and tendon reconstructions.

Effect of different resistance-training protocols on the extracellular matrix of the calcaneal tendon of rats

The calcaneal tendon extracellular matrix (ECM) is composed of collagen, non-collagenous glycoproteins and proteoglycans, and able to adapt to various biomechanical stimuli. The objective of this study was to analyze the response of different resistance-training protocols, such as hypertrophy, strength and resistance, on the organization of the calcaneal tendon after training. Wistar rats were divided into four groups: untrained (UT), resistance training (RT), hypertrophy training (HT), and strength training (ST). The protocol in a vertical climbing platform was performed thrice per week over twelve weeks. For biochemical study, the tendons of each group were minced and analyzed for gelatinases, quantification of non-collagenous proteins, sulfated glycosaminoglycans, and hydroxyproline. For morphological analysis, sections were stained with HE and toluidine blue. Non-stained sections were used for birefringence analysis under polarization microscopy. The highest hydroxyproline concentrations were found in HT (154.8±14.2) and RT (173.6±25.2) compared with UT (122.4±27.0). A higher concentration of non-collagenous proteins was detected in the RT group (14.98mg/g) compared with the other groups. In polarization microscopy, major birefringence was observed in HT and the lowest in ST compared with UT, indicating higher organization of collagen bundles in HT. In analysis for zymography, the presence of latent MMP-9 was more prominent in the ST group and the active MMP-9 more prominent in the HT group. For MMP-2, significant differences in the latent isoform between the HT (184,867±6765) and UT (173,018±9696) groups were found. In sections stained with toluidine blue (TB), higher metachromasia was observed in the tendon's distal region in HT and RT groups, indicating a greater amount of proteoglycans. We conclude that the different training protocols produced different responses in the ECM. The remarkable presence of MMP-2 and -9 in the hypertrophy training group may be related to the highest organization of collagen bundles and possibly a more efficient remodeling process, observed in that group, as demonstrated by images and measurements of birefringence.

The effects of cyclosporin A and Heteropterys tomentosa on the rat liver

Cyclosporin A (CsA) is a widely employed immunosuppressive drug that is associated with several side effects, among then hepatotoxicity. Heteropterys tomentosa is a Brazilian plant efficient in reducing damage caused by CsA on the rat testis and prostate. The aim of this study was to evaluate the effect of CsA and H. tomentosa (administered isolated or simultaneously) on the liver of Wistar rats. The animals were treated daily with water (control), CsA (15 mg/kg/day), H. tomentosa infusion or CsA+H. tomentosa, for 21 or 56 days. The treatments did not alter liver morphology or cause fibrosis. H. tomentosa administered for 21 days increased the number of hepatocyte nuclei and Kupffer cell volumetric proportion. After 56 days of treatment, H. tomentosa administration did not alter the parameters analyzed. Biochemical plasma dosages and liver stereology showed impairment caused by CsA-treatment after 21 days; these results were not observed after 56 days of treatment. The simultaneous treatment with CsA and H. tomentosa for 21 or 56 days did not alleviate nor accentuate CsA hepatic effects. The present study showed that the 21 days treatment with CsA caused more alteration to the liver than the 56 days treatment; this could be related to hepatic recovery after the long term treatment.

Exhaustive exercise with different rest periods changes the collagen content and MMP-2 activation on the calcaneal tendon

Tendons adapt to different mechanical stimuli through a remodeling process involving metalloproteinases (MMPs) and collagen synthesis. The purpose of this study was to investigate the activities of MMP-2 and MMP-9 and the collagen content in tendons after exhaustive acute exercise sessions over the course of 1, 3, or 6 days, with 1-hr or 3-hr rest periods between each session. Wistar rats were grouped into control (C), trained with 1-hr (groups 1d1h, 3d1h, and 6d1h) and trained with 3-hr (groups 1d3h, 3d3h and 6d3h) groups with rest periods between the treadmill running sessions, for 1, 3, and 6 days. The analysis of MMP-2 showed a larger presence of the latent isoform in the 1d3h group and a larger presence of the active isoform in the 6d3h group compared to the control. No differences were detected for MMP-9. A lower concentration of hydroxyproline was found in the 6d3h group compared to the 6d1h group. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed more prominent collagen bands in the 6d3h group, which was confirmed by Western blotting for collagen type I. A higher concentration of glycosaminoglycans was observed in the 3d3h group compared to the 3d1h group, and the 6d3h group presented the highest value for non-collagenous proteins compared to other groups. In conclusion, different rest periods between exercise sessions had different effects on the composition of the calcaneal tendon because a greater activation of MMP-2 and a reduction of total collagen were observed on day 6 of exercise with 3-hr rest periods compared to 1-hr rest periods.

Informal Trade of Psychoactive Herbal Products in the City of Diadema, SP, Brazil: Quality and Potential Risks

The present study aimed to assess the quality and risks involved in the consumption of psychoactive herbal products (PHs) that are available through informal commerce in the city of Diadema, SP, Brazil. Methods of ethnography were used to conduct the fieldwork during which four dealers were selected to record the collection, handling, packaging, types of PHs marketed, and their therapeutic purposes. In addition, lots of the PHs selected were purchased from the dealers and analyzed using microbiology and pharmacognosy techniques. 217 PHs were recorded and categorized into two main groups: stimulants (67%) and depressants (27%) of the central nervous system; sixteen of them were selected, and their 52 lots were acquired. The deficiencies observed in handling and packaging these lots by dealers were confirmed by microbiological analysis; 80.8% of them presented risk according to the indicators defined by the Brazilian Pharmacopoeia. The pharmacognostic analysis confirmed the authenticity of only 9 to 16 PHs analyzed. In addition, descriptions of contraindications, adverse reactions, and drug interactions were found in the literature for the PHs. The results of this study allow the observation of the priorities for the sanitary adequacy of the popular trade of herbs.

Heteropterys tomentosa (A. Juss.) infusion counteracts Cyclosporin a side effects on the ventral prostate

BACKGROUND

Cyclosporin A (CsA) is an immunosuppressive drug widely used in treatment of auto-immune diseases or after organ transplants. However, several side effects are commonly associated with CsA long term intake, some regarding to loss of reproductive organ function due to oxidative damage. Considering that phytotherapy is an important tool often used against oxidative stress, we would like to describe the beneficial effects of Heteropterys tomentosa intake to minimize the damage caused by CsA to the ventral prostate tissue of Wistar rats under laboratorial conditions.

METHODS

Thirty adult Wistar rats (Rattus norvegicus albinus) were divided into: control group (water); CsA group (Cyclosporin A); Ht group (H. tomentosa infusion) and CsA + Ht group (CsA and H. tomentosa infusion). Plasmic levels of hepatotoxicity markers, triglycerides, cholesterol and glucose were quantified. The ventral prostate tissue was analyzed under light microscopy, using stereological, morphometrical and immunohistochemical techniques.

RESULTS

H. tomentosa did not cause any alterations either of the plasmic parameters or of the ventral prostate structure. CsA caused alterations of GOT, total and indirect bilirubin, cholesterol, triglycerides and glucose levels in the plasma; CsA-treated rats showed alterations of the ventral prostate tissue. There were no alterations regarding the plasma levels of GOT, triglycerides and glucose of CsA + Ht animals. The same group also showed normalization of most of the parameters analyzed on the ventral prostate tissue when compared to the CsA group. The treatments did not alter the pattern of AR expression or the apoptotic index of the ventral prostate epithelium.

CONCLUSIONS

The results suggest a protective action of the H. tomentosa infusion against the side effects of CsA on the ventral prostate tissue, which could also be observed with plasmic biochemical parameters.