Time filter

Source Type

San Juan de la Rambla, Spain

Reyes R.,University of La Laguna | Delgado A.,University of La Laguna | Sanchez E.,University of La Laguna | Fernandez A.,NASA | And 2 more authors.
Journal of Tissue Engineering and Regenerative Medicine | Year: 2014

Regeneration of cartilage defects can be accelerated by localized delivery of appropriate growth factors (GFs) from scaffolds. In the present study we analysed the in vitro and in vivo release rates and delivery efficacies of transforming growth factor-β1 (TGFβ1) and bone morphogenetic protein-2 (BMP-2) from a bilayered system, applied for osteochondral defect repair in a rabbit model. A bone-orientated, porous PLGA cylinder was overlaid with GF containing PLGA microspheres, dispersed in an alginate matrix. Four microsphere formulations were incorporated: (a) blank ones; (b) microspheres containing 50 ng TGFβ1; (c) microspheres containing 2.5 μg BMP-2; and (d) microspheres containing 5 μg BMP-2. Release kinetics and tissue distributions were determined using iodinated (125I) GFs. Bioactivity of in vitro released BMP-2 and TGFβ1 was confirmed in cell-based assays. In vivo release profiles indicated good GF release control. 20% of BMP-2 and 15% of TGFβ1 were released during the first day. Virtually the total dose was delivered at the end of week 6. Significant histological differences were observed between untreated and GF-treated specimens, there being especially relevant short-term outcomes with 50 ng TGFβ1 and 5 μg BMP-2. Although the evaluation scores for the newly formed cartilage did not differ significantly, 5 μg BMP-2 gave rise to higher quality cartilage with improved surface regularity, tissue integration and increased collagen-type II and aggrecan immunoreactivity 2 weeks post-implantation. Hence, the bilayered system controlled GF release rates and led to preserved cartilage integrity from 12 weeks up to at least 24 weeks. © 2012 John Wiley & Sons, Ltd.

Delgado J.J.,University of La Laguna | Sanchez E.,University of La Laguna | Baro M.,Hospiten Rambla Ltd | Reyes R.,University of La Laguna | And 2 more authors.
Journal of Materials Science: Materials in Medicine | Year: 2012

Platelet derived growth factor (PDGF) was formulated in a calcium phosphate/biodegradable polymer system for local and controlled delivery to enhance bone regeneration. Implants with a porosity of 67 %, composed of hydroxyapatite, PLGA microspheres and Pluronic®, were obtained by compression. An increase in porosity with time was expected due to Pluronic®dissolution and PLGA microsphere degradation. In vivo PDGF release and tissue distribution were monitored after system implantation into femurs of rabbits using 125I-PDGF. Most of the PDGF was released within approximately 5 days and remained located around the implantation site with negligible systemic exposure. Compared with the reference groups, an important enhancement of bone regeneration was found with doses of 600 and 1,200 ng of PDGF, although no histological differences were observed between the two doses. In conclusion, the elaborated system exhibited good biocompatibility and offered a physiologically relevant PDGF profile that enhances bone formation compared to the non-treated bone defect. © 2012 Springer Science+Business Media, LLC.

Hernandez A.,University of La Laguna | Hernandez A.,Hospiten Rambla Ltd | Reyes R.,University of La Laguna | Sanchez E.,University of La Laguna | And 3 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2012

Bone regeneration and vascularization with porous PLGA scaffolds loaded with VEGF (0.35 and 1.75 μg) and BMP-2 (3.5 and 17.5 μg), incorporated in PLGA microspheres, or the combination of either dose of BMP-2 with the low dose of VEGF were investigated in an intramedullary femur defect in rabbits. The system was designed to control growth factor (GF) release and maintain the GFs localized within the defect. An incomplete release was observed in vitro whereas in vivo VEGF and BMP-2 were totally delivered during 3 and 4 weeks, respectively. A weak synergistic effect of the dual delivery of VEGF and BMP-2 (high dose) was found by 4 weeks. However, the absence of an apparent synergistic long-term effect (12 weeks) of the combination over BMP-2 alone suggests that more work has to be done to optimize VEGF dose, sequential presentation, and the ratio of the two GFs to obtain a beneficial bone repair response. Copyright © 2012 Wiley Periodicals, Inc.

Reyes R.,University of La Laguna | Delgado A.,University of La Laguna | Solis R.,CSIC - Institute of Polymer Science and Technology | Sanchez E.,University of La Laguna | And 3 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2014

This study aimed to analyze the in vitro and in vivo release kinetics and evaluate the grades of repair induced by either the release of 50 ng of transforming growth factor-β1 or 2.5 or 5 μg of bone morphogenetic protein-2 (BMP-2) from a bilayer scaffold of segmented polyurethane/polylactic- co-glycolic (SPU/PLGA) in osteochondral defects, in a rabbit model. The scaffold consisted of a porous, bone-directed PLGA layer, overlaid with a cartilage-directed layer of growth factor (GF)-loaded PLGA microspheres, dispersed in a matrix of SPU. The PLGA porous layer was fabricated by gas foaming. Microspheres were prepared by a double emulsion method. SPU was synthesized by following the two-step method. GF release kinetics were assessed using iodinated (125I) GFs. The in vivo release profiles of both GFs fitted to zero-order kinetics, demonstrating a consistently good control of their release rates by SPU. Cartilage-like tissue, characterized by histological analysis, scoring, and immunolabeling of chondrogenic differentiation markers, was observed only after 12 weeks, maintaining integrity up to at least 24 weeks, independently of the GF and the dose of BMP-2. The biocompatibility and the resulting good quality, hyaline repair cartilage convert this system into a promising candidate for future applications in osteochondral lesions. © 2013 Wiley Periodicals, Inc.

Discover hidden collaborations