Considering the Value of 3D Cultures for Enhancing the Understanding of Adhesion, Proliferation, and Osteogenesis on Titanium Dental Implants

BACKGROUND

Individuals with pathologic conditions and restorative deficiencies might benefit from a combinatorial approach encompassing stem cells and dental implants; however, due to the various surface textures and coatings, the influence of titanium dental implants on cells exhibits extensive, wide variations. Three-dimensional (3D) cultures of stem cells on whole dental implants are superior in testing implant properties and were used to examine their capabilities thoroughly.

MATERIALS AND METHODS

The surface micro-topography of five titanium dental implants manufactured by sandblasting with titanium, aluminum, corundum, or laser sintered and laser machined was compared in this study. After characterization, including particle size distribution and roughness, the adhesion, proliferation, and viability of adipose-derived stem cells (ADSCs) cultured on the whole-body implants were tested at three time points (one to seven days). Finally, the capacity of the implant to induce ADSCs' spontaneous osteoblastic differentiation was examined at the same time points, assessing the gene expression of collagen type 1 (coll-I), osteonectin (osn), alkaline phosphatase (alp), and osteocalcin (osc).

RESULTS

Laser-treated (Laser Mach and Laser Sint) implants exhibited the highest adhesion degree; however, limited proliferation was observed, except for Laser Sint implants, while viability differences were seen throughout the three time points, except for Ti Blast implants. Sandblasted surfaces (Al Blast, Cor Blast, and Ti Blast) outpaced the laser-treated ones, inducing higher amounts of coll-I, osn, and alp, but not osc. Among the sandblasted surfaces, Ti Blast showed moderate roughness and the highest superficial texture density, favoring the most significant spontaneous differentiation relative to all the other implant surfaces.

CONCLUSIONS

The results indicate that 3D cultures of stem cells on whole-body titanium dental implants is a practical and physiologically appropriate way to test the biological characteristics of the implants, revealing peculiar differences in ADSCs' adhesion, proliferation, and activity toward osteogenic commitment in the absence of specific osteoinductive cues. In addition, the 3D method would allow researchers to test various implant surfaces more thoroughly. Integrating with preconditioned stem cells would inspire a more substantial combinatorial approach to promote a quicker recovery for patients with restorative impairments.

Assessing the Efficacy of Whole-Body Titanium Dental Implant Surface Modifications in Inducing Adhesion, Proliferation, and Osteogenesis in Human Adipose Tissue Stem Cells

BACKGROUND

Although the influence of titanium implants' micro-surface properties on titanium discs has been extensively investigated, the research has not taken into consideration their whole-body effect, which may be considered possible using a combinatorial approach.

METHODS

Five titanium dental implants with a similar moderate roughness and different surface textures were thoroughly characterized. The cell adhesion and proliferation were assessed after adipose-tissue-derived stem cells (ADSCs) were seeded on whole-body implants. The implants' inductive properties were assessed by evaluating the osteoblastic gene expression.

RESULTS

The surface micro-topography was analyzed, showing that hydroxyapatite (HA)-blasted and bland acid etching implants had the highest roughness and a lower number of surface particles. Cell adhesion was observed after 24 h on all the implants, with the highest score registered for the HA-blasted and bland acid etching implants. Cell proliferation was observed only on the laser-treated and double-acid-etched surfaces. The ADSCs expressed collagen type I, osteonectin, and alkaline phosphatase on all the implant surfaces, with high levels on the HA-treated surfaces, which also triggered osteocalcin expression on day seven.

CONCLUSIONS

The findings of this study show that the morphology and treatment of whole titanium dental implants, primarily HA-treated and bland acid etching implants, impact the adherence and activity of ADSCs in osteogenic differentiation in the absence of specific osteo-inductive signals.

Abstract P3-10-07: Uptake of risk reducing measures in healthy BRCA 1-2 mutation carriers from Northern Italy: Outcomes of 9 years of close-surveillance. Experience of the hereditary cancer clinic in the region of Veneto, Italy

Background: There are several options for cancer reduction in women with a BRCA 1-2 mutation, including prophylactic surgery, chemo-prevention and close surveillance. Each of these measures offers varying levels of effectiveness with prophylactic mastectomy (PM) and oophorectomy (PO) providing the greatest risk reduction for the development of breast and ovarian cancer. The uptake of preventive procedures, however, differs according to country, not only in relation to access to care, but also cultural preferences. Here we present data on the experience of the Hereditary Cancer Center at the Istituto Oncologico Veneto, which is one of the few centers in Northern Italy to offer not only genetic testing, but also long-term follow-up to healthy carriers of the BRCA 1-2 genes. Methods: 106 healthy women were identified within a cohort of BRCA positive individuals followed since 2008. Upon learning of their BRCA mutation carrier status, they all agreed to enroll in a long-term protocol of close-surveillance. All women were also informed about risk-reducing surgery such as PO and PM. Results: The age in this sample ranged between 20 and 77 years with a median of 41.5. The average follow-up time was 4.3 +/-2.4 years. We observed that PO was more commonly accepted (41% 44/106) than PM (11% 12/106). The mean age at the time of PO was 47.3. In the PM group, half of the women decided to undergo such procedure only after being diagnosed with breast cancer. The mean age at the time of PM in the healthy subjects was 41.8 years.

Over the follow-up period, 9.4% of the patients (10/106) developed BRCA related malignancies, of which 9 breast and 1 ovarian cancer. Of the 9 breast events, 2 were diagnosed at stage 0, 2 at stage I, 3 at stage II, and 2 at stage III. All cancer cells were aggressive (grade 3). Of the 2 stage III breast tumors, 1 was diagnosed on the very 1st breast MRI screening, and the other after an interval of 3 years due to the patient being pregnant and then breastfeeding. The 3 cases of stage II breast cancer, despite being 1 cm or less in size, already had node involvement. Both stage III breast tumors were triple negative in BRCA 1 carriers. The other breast cancers were ER+ and none was Her2+. Of the ER+ breast events 4 occurred in BRCA2 and 2 in BRCA1 carriers. Except for the 2 Stage 0 tumors, which arose in women who had a previous oophorectomy, all the other breast malignancies developed in carriers who still had their ovaries and were premenopausal. The one serous ovarian cancer was diagnosed at Stage II in a 77 years-old BRCA1+ woman.

Conclusions: In this sample of healthy northern Italian women carriers of BRCA mutations, close to 10% developed a tumor within 5 years of follow-up with an aggressive cell phenotype. The more accepted method of risk-reduction in this group of women was PO as compared to PM. A protocol of close-surveillance allows for an early stage diagnosis in about half of the women who develop a breast tumor.

Citation Format: Rastelli A, Azzolin F, Tognazzo S, Alducci E, Zovato S. Uptake of risk reducing measures in healthy BRCA 1-2 mutation carriers from Northern Italy: Outcomes of 9 years of close-surveillance. Experience of the hereditary cancer clinic in the region of Veneto, Italy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-10-07.