Strength and stiffness of repaired tendons

Rotator cuff tears of the shoulder are a common cause of pain and disability. Although surgery is frequently beneficial, re-tearing of the tendons is likely to re-occur. In many cases even if the reparation is successful it will still generate discomfort, problems with mobility, as well as a sharp pain. This project is funded in the cooperation with the Hospital Clinico San Carlos de Madrid. The purpose of this work is to analyze the effect of the surgical repair and the application of different therapies, including mesenchymal stem cell therapy on the biomechanical properties (strength and stiffness) of the repaired tendon. An animal model of rotator cuff tendon reparations has been developed on laboratory rats.To obtain the mechanical response of the healthy and repaired tendons, it was necessary to develop an experimental set up to reproduce the in-vivo working conditions of the tendons (37 ºC, immersed in physiological serum), and especially the load transfer. The biomechanical properties (maximum load and stiffness) have been measured in healthy and repaired tendons. A total of 70 rats are used in this particular study. It has been found that the repaired tendon is stronger than the original on. However, the repaired tendons demonstrate less flexibility than the healthy (original) ones prior to the damage

Human midbrain precursors activate the expected developmental genetic program and differentiate long-term to functional A9 dopamine neurons in vitro. Enhancement by Bcl-XL

Understanding the molecular programs of the generation of human dopaminergic neurons (DAn) from their ventral mesencephalic (VM) precursors is of key importance for basic studies, progress in cell therapy, drug screening and pharmacology in the context of Parkinson's disease. The nature of human DAn precursors in vitro is poorly understood, their properties unstable, and their availability highly limited. Here we present positive evidence that human VM precursors retaining their genuine properties and long-term capacity to generate A9 type Substantia nigra human DAn (hVM1 model cell line) can be propagated in culture. During a one month differentiation, these cells activate all key genes needed to progress from pro-neural and prodopaminergic precursors to mature and functional DAn. For the first time, we demonstrate that gene cascades are correctly activated during differentiation, resulting in the generation of mature DAn. These DAn have morphological and functional properties undistinguishable from those generated by VM primary neuronal cultures. In addition, we have found that the forced expression of Bcl-XL induces an increase in the expression of key developmental genes (MSX1, NGN2), maintenance of PITX3 expression temporal profile, and also enhances genes involved in DAn long-term function, maintenance and survival (EN1, LMX1B, NURR1 and PITX3). As a result, Bcl-XL anticipates and enhances DAn generation.

Low-Intensity Pulsed Ultrasound Improves the Functional Properties of Cardiac Mesoangioblasts

Cell-based therapy is a promising approach for many diseases, including ischemic heart disease. Cardiac mesoangioblasts are committed vessel-associated progenitors that can restore to a significant, although partial, extent, heart structure and function in a murine model of myocardial infarction. Low-intensity pulsed ultrasound (LIPUS) is a noninvasive form of mechanical energy that can be delivered into biological tissues as acoustic pressure waves, and is widely used for clinical applications including bone fracture healing. We hypothesized that the positive effects of LIPUS on bone and soft tissue, such as increased cell differentiation and cytoskeleton reorganization, could be applied to increase the therapeutic potential of mesoangioblasts for heart repair. In this work, we show that LIPUS stimulation of cardiac mesoangioblasts isolated from mouse and human heart results in significant cellular modifications that provide beneficial effects to the cells, including increased malleability and improved motility. Additionally, LIPUS stimulation increased the number of binucleated cells and induced cardiac differentiation to an extent comparable with 5´-azacytidine treatment. Mechanistically, LIPUS stimulation activated the BMP-Smad signalling pathway and increased the expression of myosin light chain-2 together with upregulation of β1 integrin and RhoA, highlighting a potentially important role for cytoskeleton reorganization. Taken together, these results provide functional evidence that LIPUS might be a useful tool to explore in the field of heart cell therapy