RESUMEN
When traumatic injury, tumor removal, or disease results in significant bone loss, reconstructive surgery is required. Bone grafts are used in orthopedic reconstructive procedures to provide mechanical support and promote bone regeneration. In this study, we applied a heat sintering technique to fabricate 3D electrospun scaffolds that were used to evaluate effects of mineralization and fiber orientation on scaffold strength. We electrospun PLLA/gelatin scaffolds with a layer of PDLA and heat sintered them into three-dimensional cylindrical scaffolds. Scaffolds were mineralized by incubation in 10× simulated body fluid for 6, 24, and 48 h to evaluate the effect of mineralization on scaffolds compressive mechanical properties. The effects of heat sintering hydroxyapatite (HA) microparticles directly to the scaffolds on mineral deposition, distribution and mechanical properties of the scaffolds were also evaluated. We found that orientation of the fibers had little effect on the compressive mechanical properties of the scaffolds. However, increasing the mineralization times resulted in an increase in compressive mechanical properties. Also, the direct addition of HA microparticles had no effect on the scaffold mechanical properties, but had a significant effect on the mineral deposition on PLLA/gelatin scaffolds.
Asunto(s)
Huesos/fisiología , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Animales , Antraquinonas , Huesos/efectos de los fármacos , Calcificación Fisiológica/efectos de los fármacos , Durapatita/farmacología , Humanos , Ácido Láctico/farmacología , Fenómenos Mecánicos/efectos de los fármacos , Microscopía Electrónica de Rastreo , Poliésteres , Polímeros/farmacología , Coloración y Etiquetado , Sus scrofaRESUMEN
We investigated different techniques to enhance calcium phosphate mineral precipitation onto electrospun poly((L)-lactide) (PLLA) scaffolds when incubated in concentrated simulated body fluid (SBF), 10×SBF. The techniques included the use of vacuum, pre-treatment with 0.1 M NaOH and electrospinning gelatin/PLLA blends as means to increase overall mineral precipitation and distribution throughout the scaffolds. Mineral precipitation was evaluated using environmental scanning electron microscopy, energy dispersive spectroscopy mapping and the determination of the mineral weight percents. In addition we evaluated the effect of the techniques on mechanical properties, cellular attachment and cellular proliferation on scaffolds. Two treatments, pre-treatment with NaOH and incorporation of 10% gelatin into PLLA solution, both in combination with vacuum, resulted in significantly higher degrees of mineralization (16.55 and 15.14%, respectively) and better mineral distribution on surfaces and through the cross-sections after 2 h of exposure to 10×SBF. While both scaffold groups supported cell attachment and proliferation, 10% gelatin/PLLA scaffolds had significantly higher yield stress (1.73 vs 0.56 MPa) and elastic modulus (107 vs 44 MPa) than NaOH-pre-treated scaffolds.
Asunto(s)
Huesos/citología , Fosfatos de Calcio/química , Ácido Láctico/química , Minerales/química , Polímeros/química , Ingeniería de Tejidos , Andamios del Tejido/química , Células 3T3 , Animales , Fosfatos de Calcio/farmacología , Proliferación Celular/efectos de los fármacos , Precipitación Química , Cinética , Fenómenos Mecánicos , Ratones , Poliésteres , Hidróxido de Sodio/químicaRESUMEN
The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee; it also contributes to normal knee function and stability. Due to its poor healing potential severe ACL damage requires surgical intervention, ranging from suturing to complete replacement. Current ACL replacements have a host of limitations that prevent their extensive use. Investigators have begun to utilize tissue-engineering techniques to create new options for ACL repair, regeneration and replacement. In this study we tested novel braid-twist scaffolds, as well as braided scaffolds, twisted fiber scaffolds and aligned fiber scaffolds, for use as ACL replacements composed of poly(L-lactic acid) fibers. Scaffolds were examined using stress relaxation tests, cell viability assays and scanning electron microscopy. The behaviors of the braid-twist scaffolds were modeled with Maxwell and quasi-linear viscoelastic (QLV) models. In stress relaxation tests, the braid-twist scaffolds behaved similarly to native ACL tissue, with final normalized stresses of 87% and 83% after an 8 N load. There was agreement between the experimental data and the Maxwell model when the model included an element for each structural element in the scaffold. There was also agreement between the experimental data and QLV model, scaffolds with similar braiding angles shared constants. In cell proliferation studies no differences were found between fibroblast growth on the braided scaffolds and the braid-twist scaffolds. SEM images showed the presence of new extracellular matrix. Data from this and previous tensile studies demonstrate that the braid-twist scaffold design may be effective in scaffolds for ACL tissue regeneration.