RESUMEN
PURPOSE: In this study, pore size and porosity distribution of porous Ti-6Al-4V scaffolds (pTi) were controlled by 3D printing. The effects of pore size distribution at a constant porosity, or porosity distribution at a constant pore size pertaining to functions of adhesion, proliferation, and differentiation of the mouse embryonic osteoblast precursor (MC3T3-E1) cells were researched separately. METHODS: 3D printing was used to design five groups of pTi, designated as PS300/HP, PS300/LP, PS500/HP, PS500/LP, and PS800/HP based on pore size and porosity distribution. MC3T3-E1 cells were cultured on pTi, and non-porous Ti-6Al-4V samples (npTi) were prepared as control. The pTi was characterized with the scanning electron microscopy (SEM). MC3T3-E1 cells were stained via AlamarBlue assay and viability and proliferation analyzed. The mRNA levels of alkaline phosphatase (ALP), osteocalcin (OCN), collagentype-1 (Col-1), and runt-related transcription factor 2 (Runx2) in MC3T3-E1 cells were analyzed by real-time PCR analysis. RESULTS: The average pore size and porosity of pTi were recorded as (301 ± 9 µm, 58.8 ± 1.8%), (300 ± 9 µm, 43.4 ± 1.3%), (501 ± 11 µm, 58.3 ± 1.2%), (499 ± 12 µm, 42.7 ± 1.1%), and (804 ± 10 µm, 58.9 ± 1.3%), respectively. SEM images confirmed active attachment of cells and oriented with the direction of metal rod after pTi/MC3T3-E1 co-culture for 3 and 7 days. In addition, MC3T3-E1 cells grown on the PS800/HP displayed significantly higher proliferation compared with each group after 3 days incubation (p < 0.05). Moreover, cells showed some degree of proliferation in all groups, with the highest value recorded for PS800/HP after culture for 7 days (p < 0.05). The gene expression pattern of ALP, OCN, Col-1, and Runx2 confirmed that these were down-regulated when pore size increased or porosity decreased of pTi (p < 0.05). CONCLUSION: The pTi facilitated the adhesion and differentiation of osteoblast when pore size decreased or porosity increased. The scaffold model resembles physical modification with porous structures, which has potential application in the surface modifications of Ti implant.
Asunto(s)
Aleaciones/química , Diferenciación Celular/efectos de los fármacos , Osteoblastos/metabolismo , Porosidad , Impresión Tridimensional , Titanio/química , Células 3T3 , Animales , Materiales Biocompatibles/química , Adhesión Celular , Proliferación Celular , Supervivencia Celular , Ensayo de Materiales , Ratones , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Andamios del Tejido/químicaRESUMEN
The 2004 Southeast Asia Tsunami killed nearly 5,400 people in Southern Thailand, including foreign tourists and local residents. To recover DNA evidence as much as possible from the seriously decomposed bodies, we explored procedures of sample preparation from both bone and tooth samples as well as both mitochondrial and nuclear markers. Despite having failed to recover enough DNA for nuclear marker typing, we succeeded in obtaining fully informative results for mitochondrial markers (HV1 and HV2) from 258 tooth samples with a success rate of 51% (258/507). Using an organic DNA extraction method coupled with an ultrafiltration step, we obtained 16 STR (including 13 CODIS loci, one sex discrimination locus, and two Identifiler loci) profiles for 834 samples with a success rate of 79% (834/1,062). In addition, by comparing the allelic frequencies between the typed samples as a group and other index populations, we conclude that the Thai tsunami victims are a combined group of several populations. Our results provide valuable evidence and protocols for the future forensic practice.