Biomedical subjects

Nestor Torio Padron

Publications and source records attributed to Nestor Torio Padron.

7 recordsLinked to original sources

PubMed2006

Endoscopic transaxillary subpectoral augmentation mammaplasty: a safe and predictable procedure.

During the last decades breast augmentation has gained worldwide acceptance. In addition to the inframammary and periareolar approach for augmentation mammaplasty, the transaxillary route provides an elegant means of retaining the integrity of the breast mound by avoiding visible scars. Due to concerns as to the safety of this technique we analysed 47 patients who underwent endoscopy-assisted transaxillary submuscular augmentation mammaplasty in our department from 1999 to 2004. The inclusion criteria were aesthetic breast augmentation due to breast hypoplasia. Patients with a history of breast cancer, other malignancies, or previously performed mastectomy were excluded. Procedures for tuberous breast deformity as well as concomitantly performed mastopexy were also excluded. No complications were observed impairing final outcome or requiring early operative intervention, such as infection or haematoma. This technique is suitable for patients who prefer a hidden incision at a distant site, and provides predictability of aesthetic outcome and is safe.

Adult↗

PubMed2006

Porous poly(DL-lactic-co-glycolic acid)/calcium phosphate cement composite for reconstruction of bone defects.

Calcium phosphate (Ca-P) cements are injectable, self-setting ceramic pastes generally known for their favorable bone response. Ingrowth of bone and subsequent degradation rates can be enhanced by the inclusion of macropores. Initial porosity can be induced by CO(2) foaming during setting of the cement, whereas secondary porosity can develop after hydrolysis of incorporated poly(DL-lactic- co-glycolic acid) (PLGA) microparticles. In this study, we focused on the biological response to porous PLGA/Ca-P cement composites. Pre-set composite discs of four formulations (4 wt% or 15 wt% PLGA microparticles and low or high CO(2) induced porosity) were implanted subcutaneously and in cranial defects in rats for 12 weeks. Histological analysis of the explanted composites revealed that bone and fibrous tissue ingrowth was facilitated by addition of PLGA microparticles (number average diameter of 66 +/- 25 microm). No adverse tissue reaction was observed in any of the composites. Significant increases in composite density due to bone ingrowth in cranial implants were found in all formulations. The results suggest that the PLGA pores are suitable for bone ingrowth and may be sufficient to enable complete tissue ingrowth without initial CO(2) induced porosity. Finally, bone-like mineralization in subcutaneous implants suggests that, under appropriate conditions and architecture, porous PLGA/Ca-P cement composites can exhibit osteoinductive properties. These PLGA/Ca-P composites are a promising scaffolding material for bone regeneration and bone tissue engineering.

Absorbable Implants↗

PubMed2005

Biocompatibility and degradation of poly(DL-lactic-co-glycolic acid)/calcium phosphate cement composites.

Injectable calcium phosphate (Ca-P) cement materials exhibit favorable osteocompatible behavior but are resorbed slowly because of a lack of a bone ingrowth-enabling macroporosity. In this study, poly(DL-lactic-co-glycolic acid) (PLGA) microparticles (average size 66 +/- 25 microm) were incorporated into Ca-P cement to obtain a macroporous Ca-P cement scaffold after PLGA hydrolysis in vivo. Preset PLGA/Ca-P cement composite discs of various weight ratios (0/100, 15/85, 30/70, and 50/50) were implanted subcutaneously and in cranial defects in rats for 12 weeks. Histological analysis revealed that all macropores in the PLGA-containing composites (average pore size 73 +/- 27 microm) were filled with fibrous tissue and blood vessels (subcutaneous implants) and/or bone (cranial implants). Histologically, bone formation appeared most abundant and most consistent in the 30/70 PLGA/Ca-P cement composites. Histomorphometrical evaluation revealed a significant increase in defect fill in the 15/85 and 30/70 PLGA/Ca-P cement composites. Finally, subcutaneous and cranial 50/50 PLGA/Ca-P cement composites had degraded to a large extent, without adequate replacement by bone in the cranial implants. Therefore, we conclude that PLGA/Ca-P cement composites enable tissue ingrowth and show excellent osteocompatibility in weight ratios of 15/85 and 30/70 PLGA/Ca-P cement. In this model, 30/70 PLGA/Ca-P cement composites showed the most favorable biological response.

Absorbable Implants↗

PubMed2003

Chorioallantoic membrane angiogenesis model for tissue engineering: a new twist on a classic model.

Tissue-engineering (TE) applications include the isolation, culture, and seeding of cells into a suitable matrix or scaffold before in vivo transplantation. After transplantation, vascularization of the scaffold is a principal limiting factor for cell viability for the first 6-8 days posttransplantation. A model for systematic analysis of this process has been developed. Fertilized White Leghorn eggs were incubated (at 37.8 degrees C in 60% relative humidity) and opened on day 3 of incubation. Preadipocyte-seeded fibrin constructs were implanted in a specially designed plastic cylinder and placed through the opening on the surface of the chorioallantoic membrane (CAM) on day 8 of incubation. Vascularization of the constructs by chorioallantoic blood vessels was assessed for up to 8 days posttransplantation. The survival rate for embryos receiving transplanted constructs was about 90%. Histology confirmed transplant cell viability at day 4 posttransplantation and vascularization of the constructs by avian endothelial cells began at this time. A new in vivo model to study the effect of angiogenesis in TE constructs, including assessments of viability, proliferation, and differentiation of transplanted cells and biomaterial properties, is presented. Advantages include easy access to the vascular network of the CAM, lack of immunocompetence, low costs, and avoidance of animal experiments.

Allantois↗

PubMed2003

Engineered adipose tissue supplied by functional microvessels.

A volume-persistent culture of adipose tissue under in vivo conditions can be achieved only by early vascularization after cell transplantation. Cotransplantation of autologous preadipocytes with endothelial cells may enable the early formation of a capillary network. Investigations were performed in vivo in a specially adapted chorioallantoic membrane (CAM) model. Fertilized White Leghorn eggs were incubated and opened on day 3 of incubation and human dermal microvascular endothelial cell (HDMVEC) spheroids and preadipocytes were transferred in a fibrin matrix to the CAM. On day 7 after incubation the composites were explanted and immunohistologically investigated. Numerous vessels consisting of HDMVECs could be detected and the lumena of these vessels were perfused by chick erythrocytes. These results show the formation of a capillary network consisting of transplanted HDMVECs. The microcirculation of chick erythrocytes in vessels consisting of human endothelial cells proves the continuity of a newly formed capillary system to the host vessel system. The experiments demonstrate the first patent connection of tissue-engineered microvessels in adipose tissue to a host vessel system without applying exogenous angiogenic growth factors or transient transfection. The cotransplantation of endothelial cell spheroids with angiogenic mesenchymal cells may lead to the engineering of complex three-dimensional implants.

Adipocytes↗

PubMed2003

rhBMP-2 release from injectable poly(DL-lactic-co-glycolic acid)/calcium-phosphate cement composites.

BACKGROUND: In bone tissue engineering, poly(DL-lactic-co-glycolic acid) (PLGA) microparticles are frequently used as a delivery vehicle for bioactive molecules. Calcium phosphate cement is an injectable, osteoconductive, and degradable bone cement that sets in situ. The objective of this study was to create an injectable composite based on calcium phosphate cement embedded with PLGA microparticles for sustained delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2). METHODS: (125) I-labeled rhBMP-2 was incorporated in PLGA microparticles. PLGA microparticle/calcium-phosphate cement composites were prepared in a ratio of 30:70 by weight. Material properties were evaluated by scanning electron microscopy, microcomputed tomography, and mechanical testing. Release kinetics of rhBMP-2 from PLGA/calcium-phosphate cement disks and PLGA microparticles alone were determined in vitro in two buffer solutions (pH 7.4 and pH 4.0) for up to twenty-eight days. RESULTS: The entrapment yield of rhBMP-2 in PLGA microparticles was a mean (and standard deviation) of 79% +/- 8%. Analysis showed spherical PLGA microparticles (average size, 17.2 +/-1.3 micro m) distributed homogeneously throughout the nanoporous disks. The average compressive strength was significantly lower (p < 0.001) for PLGA and calcium-phosphate cement composite scaffolds than for calcium-phosphate cement scaffolds alone (6.4 +/- 0.6 MPa compared with 38.6 +/- 2.6 MPa, respectively). Average rhBMP-2 loading was 5.0 +/- 0.4 micro g per 75-mm (3) disk. Release of rhBMP-2 was limited for all formulations. At pH 7.4, 3.1% +/- 0.1% of the rhBMP-2 was released from the PLGA/calcium-phosphate cement disks and 18.0% +/- 1.9% was released from the PLGA microparticles alone after twenty-eight days. At pH 4.0, PLGA/calcium-phosphate cement disks revealed more release of rhBMP-2 than did PLGA microparticles alone (14.5% +/- 6.3% compared with 5.4% +/- 0.7%) by day 28. CONCLUSIONS: These results indicate that preparation of a PLGA/calcium-phosphate cement composite for the delivery of rhBMP-2 is feasible and that the release of rhBMP-2 is dependent on the composite composition and nanostructure as well as the pH of the release medium.

Bone Cements↗

PubMedDate not supplied

Safety, complications, and satisfaction of patients undergoing submuscular breast augmentation via the inframammary and endoscopic transaxillary approach.

BACKGROUND: Since its introduction, augmentation mammaplasty has gained widespread popularity, as demonstrated by the fact that an estimated 2 million women in the United States have received implants. During recent decades, several surgical approaches have evolved in terms of implant placement or site of access to the surgical plane. Debate has existed concerning the questionable superiority of a particular technique for achievement of optimal results. Thus, the inframammary approach, an established and widely accepted technique for breast augmentation, and endoscopically assisted transaxillary breast augmentation were retrospectively compared in terms of safety and aesthetic outcome, as measured, respectively, by the rate of postoperative complications and patient satisfaction. METHODS: This study analyzed 78 patients undergoing augmentation mammaplasty between 1997 and 2004. Only patients seeking primary augmentation mammaplasty solely for aesthetic reasons were included in the study. Previously performed breast surgery and simultaneously conducted ipsilateral mastopexy were among the exclusion criteria. Patient satisfaction was assessed using the client satisfaction questionnaire (CSQ-8) because of its easy applicability. RESULTS: The complication rate was low in both patient subsets, thus confirming the safety of the transaxillary approach, as compared with the more common submammary technique. However, a higher level of satisfaction was detected in the former patient group, indicating a more favorable aesthetic outcome with the transaxillary augmentation mammaplasty. CONCLUSION: Endoscopically assisted transaxillary augmentation mammaplasty is a safe method with predictable results associated with a high level of patient satisfaction. If applied in the setting of appropriate indications, it is an excellent tool for use with patients who prefer to have an incision at a distant site.

Adolescent↗