Table 4.
Studies that fulfilled the selection criteria and were included for the review in the “Results” section—cell culture experiments
| References | Type of cells | Type of assay | Control | Results | Statistics |
|---|---|---|---|---|---|
| Human osteoblasts (OB) | |||||
| Bordji et al. [33] | OB from trabecular bone | Cell proliferation and viability test (after 14, 18, 21 days), cell protein content test | Yes | OB viability after 14, 18, 21 days (%): (1) Stst N-implanted: 94.4, 94.4, 93.4; (2) Stst C-doped: 94.3, 94.4, 93.9; (3) Stst nitrided, 70.0, 66.9, 66.4; (4) Stst untreated, 93.7, 91.8, 93.5 | t test |
| Ryhänen et al. [34] | OB from alveolar bone | Cell proliferation and viability test (after 2, 4, 6, 8 days) | Yes | Cell culture of OB revealed no toxic effect, no decrease in cell proliferation, and no inhibition on the growth of cells. Cell proliferation vs. control group (%): (1) Nitinol, 100.5; (2) Stst, 104.7; (3) Ti, 99.5; (4) Composite, 53.6 | Two-sample t test |
| Schmidt et al. [35] | OB from femur or femoral head | Cell proliferation and viability test (after 3, 7, 11, 15, 19 days) | Yes | After 19 days, 300% increase of cell number; Thermanox, Ti–6Al–7Nb, cpTi—the culture reached stationary phase, in culture on Stst—growth curve was linear, stationary phase was not reached. Cell counts after 19 daysc: (1) pure Ti (cpTi), 95,000; (2) Ti–6Al–7Nb, 95,000; (3) Stst, 120,000 (linear growth); (4) Thermanox (control), 109 000; (1, 2, 4) stationary phase reached after 15 days | Tukey–Kramer test |
| Bogdanski et al. [36] | Primary OB | Cell proliferation and adhesion test (after 3 days) | –b | Good biocompatibility for a nickel content up to 50%; the lack of biocompatibility at high nickel contents may be ascribed to the presence of elemental nickel or nickel-rich intermetallic phases; the released nickel rapidly reached cytotoxic concentrations within 1 day | –b |
| Hao et al. [37] | OB-hFOB 1.19 | Proliferation test (after 7 days), cell attachment, morphology—by SEM | Yes | Significant increase in cell proliferation | One-way ANOVA, Scheffe’s post hoc multiple-comparison test |
| Human osteoblast-like cells | |||||
| Riccio et al. [38] | Embryonic OB-like | Viability, morphology, osteogenic capacity | Yes | Studied materials did not exert any significant cytotoxic effects on cultured osteoblasts; plating efficiency, adhesion, and morphology of OB; ability of cells to proliferate around the tested materials was confirmed | –b |
| Bogdanski et al. [36] | OB-like osteosarcoma cells MG63 and SAOS-2 | –a | –a | –a | –a |
| Torricelli et al. [39] | OB-like cells-MG63 | Cell proliferation and viability test (after 3 days) with use of WST-1, morphology—SEM images | Yes | Stst P558—no negative effects on cell proliferation, activation, and differentiation compared to alloy of Ti or control; SEM images—no changes in morphology | One-way ANOVA, Scheffe’s post hoc multiple-comparison test |
| Montanaro et al. [40] | OB-like cells MG63 | Cell proliferation test (NR uptake assay, AB staining assay) | Negative and positive control | The extracts did not reduce viability or cell growth potential and therefore did not have toxic effects. Cell viability index (%)c: (1) Stst Böhler P558 (Ni-free), 100; (2) Stst AISI 316 L, 95. Cell growth index (%)c: (1) Stst Böhler P558 (Ni-free), 110; (2) Stst AISI 316 L, 102 | t test |
| Michiardi et al. [41] | OB-like cells MG63 | Cell proliferation and viability test (after 1, 3, 6, 9 days) with use of WST-1, adhesion test with use of WST1 test (after 1, 4, 8 h) | Positive (polystyrene surface) and negative (Teflon surface) control | Proliferation—untreated and oxidized NiTi surfaces are not cytotoxic; the differences of initial adhesion did not affect the proliferation; adhesion test—oxidation treatment delays cell adhesion (no stat. sign. vs. control); proliferation study—the cells continually proliferated, except for the positive control (the difference is not significant); the negative control—stat. sign. higher number of cells at each time of culture | t test, one-way ANOVA with Fishers and Tukey’s multiple-comparison tests |
| Animal osteoblasts | |||||
| Morais et al. [42] | Rabbit OB from bone marrow | Cell proliferation and viability test (after 7, 14, 21, 28 days) | Yes | Metal ions stimulate proliferation vs. control; cell proliferation increased in the presence on Ni | Double-sided t test/yes |
| Kapanen et al. [43] | Rat osteosarcoma cell line ROS—17/2.8 | Viability test (after 2 days) with use of LIVE/DEAD® Viability/Cytotoxicity Kit | –b | Ratio of dead to live cells significantly higher in Ni and Stst; Ti culture—lower death rate comparing to Stst culture. Amount of dead cells/1,000 cells: NiTi, 4; Stst, 21; Ti, 4.8; Ni, 51. Stat. sign. NiTi and Ti < Ni | ANOVA, t test with Bonferroni correction |
| Fini et al. [44] | Rat OB from trabecular bone | Cell proliferation and viability test (after 3 days) with use of WST-1 | Yes | Stst P558 enhanced osteoblast differentiation. WST1 OD at 450 nm: (1) control, 1.016; (2) P558, 1.028; (3) Ti6Al4V, 0.966 | Multiple-way ANOVA |
| Cortizo et al. [45] | Rat OB osteosarcoma derived cells UMR106 and MC3T3E1 cells | Cell growth (mitotic index) and differentiation (after 2 days) | Yes | Cu and Ag are most toxic elements; other metals are biocompatible with OB (cell survival (%), mitotic index)c: pure metals: (1) Ag 75, 0.005; (2) Au 96, 0.01; (3) Pt 100, 0.016; (4) Pd 100, 0.012; (5) Cu 3, 0; (6) Ni/Ti alloy (Nitinol) 110, 0.025; (7) control 100, 0.018 | t test; correlation by Pearson’s correlation coefficient |
| Yeung et al. [46] | Mice OB from calvarial bone | Cell proliferation, viability, and adhesion test (after 2, 4, 6, 8 days) | Yes (empty wells) | Cell proliferation (×10,000) after 2, 4, 6, 8 daysc: (1) NiTi 4.9, 10, 15.1, 17; (2) NiTi–N 4.9, 4.8, 10, 18; (3) NiTi–O 4.9, 4.2, 8, 12; (4) control 2, 6, 20, 24; | t test |
| Yeung et al. [47] | Mice OB from calvarial bone | Cell proliferation, viability, and adhesion test (after 2, 4, 6, 8 days) | Yes (not implanted material) | The best biological effect—material implanted with nitrogen | Unpaired two-sample t test |
| Wu et al. [48] | Mice OB from calvarial bone | Cell proliferation test (after 8 days), morphology—fluorescent microscopy | Yes | No immediate cytotoxic effects were found; the treated and untreated materials were well tolerated by the EGFP-expressing osteoblasts; the cells attached and proliferated | –b |
| Wu et al. [49] | Mice OB from calvarial bone | Cell proliferation test (after 8 days), morphology—fluorescent microscopy | Yes | Cell cultures showed that NiTi oxidized at 450°C—no cytotoxicity (cell proliferation and growth); the cells attached to and proliferated on the entire surface of NiTi (oxidized at 450°C and untreated); only a small amount attached to the material fabricated at 600°C | –b |
| Liu et al. [50] | Mice OB from calvarial bone | Cell proliferation and viability test (after 1 day), morphology—fluorescent microscopy | Yes |
The surface TiN layer favored osteoblast proliferation; this concerned materials implanted at higher voltages (30 and 40 kV), which adhere better than unimplanted and 20 kV PIII. Cell proliferation after 8 days, cell numberc: (1) empty well, 1,100; (2) control, 700; (3) 20 kV, 740; (4) 30 kV, 825; (5) 40 kV, 775 |
Unpaired two-sample t test |
| Yeung et al. [51] | Mice OB from calvarial bone | Cell proliferation (after 2,4, 6, 8 days) and cell viability test | Yes | Number of viable cell (×10,000) after 2, 4, 6, 8 daysc: (1) NiTi 4.9, 6, 8, 12.5; (2) NiTi–N 4.9, 5, 10, 15; (3) Stst –b, 2.5, 7, 9; (4) Ti–6Al–4V 2, 2.3, 7.5, 10.2 | Two-sample t test |
| Ochsenbein et al. [52] | Mice OB from calvarial bone—MC3T3-E1 | Cell proliferation (after 3–6 days) and viability test (Alamar-blue dye by intracellular respiratory activity), morphology—SEM | Yes | SEM—good cell attachment for all the materials; higher cell proliferation rates—SiO2–TiO2 and TiO2, and lower in Nb2O5 and SiO2; the vitality rates increased for cpTi and Nb2O5. Proliferation rate with regard to control after 6 days (%)c: (1) cpTi, 120; (2) Nb2O5, 105; (3) SiO2, 100; (4) SiO2–TiO2, 130; (5) TiO2, 125; (6) 316 L 18. Vitality test with regard to control after 6 days (%)c: (1) cpTi, 105; (2) Nb2O5, 105; (3) SiO2, 98; (4) SiO2–TiO2, 101; (5) TiO2, 103; (6) 316 L, 20 | One-way ANOVA |
| Liu et al. [53] | Mice OB from calvarial bone | Cell proliferation and viability (after 1 day), morphology—fluorescent microscopy | Yes | More cells were attached to the materials treated with 50 and 100 Hz than in the control and 200 Hz; similar results were obtained for proliferation; the majority of OB—polygonal shape and the plasma membranes—extended to all sides; many OB in the control and at 200 Hz polarized shape and elongate in opposite directions (partially spreading behavior) | –b |
aThe results are discussed in the section “Human Osteoblasts” (OB)
bNot found
cRead from the graph