P6. MSCs grown on micro-nano modified titanium-aluminum-vanadium surfaces generate osteogenic, angiogenic, and immunomodulatory factors
Osseointegration is a complex biological cascade that regulates bone regeneration after implant placement. Bone-contacting implants, designed with multiscale surface topography mimicking an osteoclast resorption pit, can augment this regenerative process through the regulation of bone marrow stromal...
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| Published in: | The spine journal Vol. 24; no. 9; p. S65 |
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| Main Authors: | , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier Inc
01-09-2024
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| Online Access: | Get full text |
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| Summary: | Osseointegration is a complex biological cascade that regulates bone regeneration after implant placement. Bone-contacting implants, designed with multiscale surface topography mimicking an osteoclast resorption pit, can augment this regenerative process through the regulation of bone marrow stromal cells (MSCs). Factors generated by the MSCs can modulate activity of osteoclasts and immune cells, impact angiogenesis, and regulate osteoblast differentiation via autocrine and paracrine mechanisms.
The goal of this study was to better understand the microenvironment created by MSCs in response to micro-nano surface features on titanium-aluminum-vanadium (Ti6Al4V) implants. MSCs were cultured on Ti6Al4V substrates with 3 different surface textures and expression of osteogenic, immunogenic, and angiogenic factors was determined using qPCR and RNA-Seq.
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With a customized RT-qPCR gene array and RNA-Seq, the relevant expression of osteogenic, inflammatory and angiogenic mediators were compared in response to different implant surface modifications in nonosteogenic media. First, MSCs were cultured for 14 days on tissue culture polystyrene (TCPS) or Ti6Al4V discs with different surface modifications: a baseline comparator (anodized), machined smooth (smooth), and acid-etched to create a biomimetic micro-nanoscale surface topography (MN). Twelve discs were used per variable and wells were pooled in duplicate (n=6) to generate sufficient mRNA for analysis. A second set of MSCs cultured on TCPS with osteogenic media (OM) containing dexamethasone and beta-glycerolphosphate was compared to MSCs cultured on the MN surface. At harvest, all conditioned media were analyzed by ELISA and cell layers homogenized in TRIzol reagent before isolation of DNase I-treated RNA for RT-qPCR and RNA-seq analysis. Statistical comparisons were made by one-way ANOVA for multiple comparisons with Bonferroni correction and statistical significance determined at p ≤ 0.05.
MSCs cultured on MN surfaces, compared to cells on anodized or smooth Ti6Al4V, exhibited significantly enhanced pro-osteogenic expression of genes encoding the osteoblastic marker, osteocalcin (BGLAP), and differentiation (BMP2, RUNX2, SP7). MN surfaces also increased pro-angiogenic factors (VEGFA, FGF2); receptors (NRP1); integrins (ITGa6, ITGb1); and pro-M2 markers (IL33); as well as reducing markers of pro-inflammatory M1 macrophage polarization (IL1α, IL1β, and IL6). RNA-Seq indicated that osteoblastic differentiation of MSCs on the MN surface in growth media was different than MSCs grown in OM. Both treatments shared expression of 199 genes; growth on MN affected 563 genes while growth on TCPS in OM affected the expression of 1025 different genes. Distinct WNT pathways were observed – WNT5A was upregulated on MN while WNT3A was upregulated on TCPS in OM – suggesting that data generated using OM to induce osteogenesis may not accurately reflect surface-mediated osteoblast differentiation.
MN surfaces, designed for bone-contacting implants, were capable of enhancing the microenvironment generated by MSCs across osteogenic, inflammatory, and angiogenic factors. The MN surface-induced increase of VEGF and decrease of M1-specific cytokines polarized macrophages toward anti-inflammatory, pro-regenerative M2 phenotypes, capable of suppressing inflammation, inducing angiogenesis, and promoting regeneration. Spinal implants engineered with MN surfaces may lead to more effective osseointegration compared to those without.
This abstract does not discuss or include any applicable devices or drugs. |
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| ISSN: | 1529-9430 |
| DOI: | 10.1016/j.spinee.2024.06.027 |