Mesenchymal stem cell (MSC) transplantation has proved to be a promising strategy in cell therapy and regenerative medicine. Although their mechanism of action is not completely clear, it has been suggested that their therapeutic activity may be mediated by a paracrine effect. The main goal of this study was to evaluate by radiographic, morphometric and histological analysis the ability of mesenchymal stem cells derived from human adipose tissue (Ad-MSC) and their conditioned medium (CM), to repair surgical bone lesions using an in vivo model (rabbit mandibles). The results demonstrated that both, Ad-MSC and CM, induce bone regeneration in surgically created lesions in rabbit's jaws, suggesting that Ad-MSC improve the process of bone regeneration mainly by releasing paracrine factors. The evidence of the paracrine effect of MSC on bone regeneration has a major impact on regenerative medicine, and the use of their CM can address some issues and difficulties related to cell transplants. In particular, CM can be easily stored and transported, and is easier to handle by medical personnel during clinical procedures.

Bone defects are the cause of functional disability and the restoration of skeletal function remains an important challenge on orthopedics, neurosurgery and oral and maxillofacial surgery. Because of the limitations of the currently used techniques for the reconstruction of bone defects and the difficulties for the implementation of new therapeutic strategies, a new paradigm in the field of reconstructive surgery has arisen, leading to tissue engineering and regenerative medicine. Mesenchymal stem cells (MSC) have emerged as a promising alternative for the treatment of bone lesions. It was postulated that the therapeutic action was the result of proliferation and differentiation of MSCs, replacing injured tissue. However, recent studies have shown that MSCs secrete a number of trophic factors that have a strong effect during repair and tissue regeneration. This represents a shift from a paradigm centered on MSC proliferation and differentiation to a new paradigm in which the MSCs exert their beneficial effect by the secretion of paracrine factors that induce endogenous repair mechanisms. This chapter will bring together basic and clinical aspects, focused on novel findings on MSC paracrine effect and the development of new therapeutic strategies based on growth factors, cytokines and signaling molecules involved in bone regeneration.

Molecules of animal or bacterial origin, which pose a risk for zoonoses or immune rejection, are commonly used for extraction, culture, and cryopreservation of mesenchymal stem cells. There is no sequential and orderly protocol for producing human adipose-derived stem cells (hASCs) under xeno-free conditions. After standardizing a human platelet lysate (hPL) production protocol, four human adipose tissue samples were processed through explants with fetal bovine serum (FBS)-supplemented or hPLsupplemented media for extracting the adipose-derived stem cells. The cells were cultivated in cell culture medium + hPL (5%) or FBS (10%). The cellular replication rate, immunophenotype, and differentiation potential were evaluated at fourth passage. Cellular viability was evaluated before and after cryopreservation of the cells, with an hPL-based solution compared with an FBS-based solution. The explants cultured in hPL-supplemented media showed earlier and faster hASC proliferation than did those supplemented with FBS. Likewise, cells grown in hPL-supplemented media showed a greater proliferation rate, without losing the immunophenotype. Osteogenic differentiation of xeno-free hASC was higher than the hASC produced in standard conditions. However, adipogenic differentiation was reduced in xeno-free hASC. Finally, the cells cryopreserved in an hPL-based solution showed a higher cellular viability than the cells cryopreserved in an FBS-based. In conclusion, we have developed a complete xeno-free protocol for extracting, culturing, and cryopreserving hASCs that can be safely implemented in clinical studies. STEM CELLS TRANSLATIONAL MEDICINE 2016;5:358-365 SIGNIFICANCEThis study was performed to standardize a complete ordered protocol to produce xeno-free human adipose-derived mesenchymal stem cells (hASCs) as a safe therapeutic alternative. Cells were extracted by adipose tissue explants and then cultured and cryopreserved using human platelet lysate (hPL). Different scientific journals have published data regarding the use of hPL as a safe fetal bovine serum substitute for hASC culture, using heparin to avoid clot formation. This article reports the use of hPL for extracting, culturing, and cryopreserving hASCs without anticoagulant.

Biomédica 2014;34:67-78 Ad-MSC en hidrogeles de plasma sanguíneo humano Contribución de los autores:Itali M. Linero: diseño de experimentos, obtención, cultivo y caracterización de las Ad-MSC, elaboración del hidrogel de plasma sanguíneo humano, escritura y revisión del manuscrito. Adriana Doncel: obtención, cultivo y caracterización de las Ad-MSC, y revisión del manuscrito. Orlando Chaparro: diseño de experimentos, escritura y revisión del manuscrito. Introducción. La utilización de las células madre mesenquimales en la práctica clínica ha aumentado considerablemente en la última década, ya que juegan un papel favorable en los procesos de reparación y regeneración tisular, siendo la principal herramienta de la terapia celular para el tratamiento de enfermedades que afectan funcionalmente el tejido óseo y cartilaginoso. Objetivo. Evaluar la proliferación y capacidad de diferenciación osteogénica in vitro de células madre mesenquimales derivadas de tejido adiposo humano en un hidrogel de plasma sanguíneo. Materiales y métodos. Se obtuvieron células madre mesenquimales a partir de explantes de tejido adiposo humano y se caracterizaron por citometría de flujo; se buscó demostrar su multipotencialidad por su capacidad de diferenciación osteogénica y adipogénica. Se evaluó la proliferación celular y la capacidad de diferenciación osteogénica de las células cultivadas en hidrogeles de plasma sanguíneo.Resultados. Las células madre mesenquimales derivadas de tejido adiposo cultivadas en el hidrogel de plasma sanguíneo humano mostraron un patrón de proliferación muy similar al de las células cultivadas en monocapa y, además, mantuvieron su capacidad de diferenciación hacia el linaje osteogénico. Conclusiones. El hidrogel de plasma sanguíneo humano es un soporte adecuado para que las células madre mesenquimales derivadas de tejido adiposo humano proliferen y se diferencien hacia el linaje osteogénico y constituye un vehículo adecuado para su administración en regeneración del tejido óseo.Palabras clave: células madre, hidrogeles, plasma, regeneración ósea.doi: http://dx.doi.org/10.7705/biomedica.v34i1.1465 Proliferation and osteogenic differentiation of mesenchymal stem cells in hydrogels of human blood plasmaIntroduction: The use of mesenchymal stem cells in clinical practice has increased considerably in the last decade because they play a supporting role in the processes of tissue repair and regeneration, becoming the main tool of cell therapy for the treatment of diseases functionally affecting bone and cartilage tissue. Objective: To evaluate in vitro the proliferative and osteogenic differentiation ability of mesenchymal stem cells derived from human adipose tissue in a blood plasma hydrogel. Materials and methods: Mesenchymal stem cells were obtained from human adipose tissue explants and characterized by flow cytometry. Their multipotentiality was demonstrated by their ability to differentiate to adipogenic and osteogenic lineages. Cell proliferation and osteogenic differentiation ability of the cells cultured...

Multiple sclerosis (MS) is a neurodegenerative, demyelinating, and chronic inflammatory disease characterized by central nervous system (CNS) lesions that lead to high levels of disability and severe physical and cognitive disturbances. Conventional therapies are not enough to control the neuroinflammatory process in MS and are not able to inhibit ongoing damage to the CNS. Thus, the secretome of mesenchymal stem cells (MSC-S) has been postulated as a potential therapy that could mitigate symptoms and disease progression. We considered that its combination with physical exercise (EX) could induce superior effects and increase the MSC-S effectiveness in this condition. Recent studies have revealed that both EX and MSC-S share similar mechanisms of action that mitigate auto-reactive T cell infiltration, regulate the local inflammatory response, modulate the proinflammatory profile of glial cells, and reduce neuronal damage. Clinical and experimental studies have reported that these treatments in an isolated way also improve myelination, regeneration, promote the release of neurotrophic factors, and increase the recruitment of endogenous stem cells. Together, these effects reduce disease progression and improve patient functionality. Despite these results, the combination of these methods has not yet been studied in MS. In this review, we focus on molecular elements and cellular responses induced by these treatments in a separate way, showing their beneficial effects in the control of symptoms and disease progression in MS, as well as indicating their contribution in clinical fields. In addition, we propose the combined use of EX and MSC-S as a strategy to boost their reparative and immunomodulatory effects in this condition, combining their benefits on synaptogenesis, neurogenesis, remyelination, and neuroinflammatory response. The findings here reported are based on the scientific evidence and our professional experience that will bring significant progress to regenerative medicine to deal with this condition.