Table 5.
Summary of the characteristics and main results of studies in rabbits (n = 7).
| Ref. | Sample Size (No. Animals) | Defect | Biomaterial(s) § | Control (Empty, DBBM, Autogenous Bone) § | Other Materials/ Treatments § |
Stem Cells, Drugs, GFs | Sacrifice (Weeks) |
Assessment Method(s) | Main Findings |
|---|---|---|---|---|---|---|---|---|---|
| [115] | 24 | Mandibular square hole 12 × 10 × 2 mm (length × width × depth) | PEEK-BBC composite doped with VEGF (n = 6) |
Empty (n = 6) |
(a) no surgery (n = 6) (b) sham group—surgery only, no defect (n = 6) |
VEGF | 4, 8, 16 | Histological analysis; histomorphometric analysis; RT-PCR; Western blot; immunofluorescence | Histological and histomorphometric analyses: the dimension of the defects in the empty group could be significantly lessened in the test group (p < 0.05). RT-PCR: 8 and 16 weeks: test group had a much higher mRNA level of VEGF than the empty group. Western blot: VEGF lower in the empty group compared with the test group (p < 0.05). Immunofluorescence: protein level of VEGF in the test group was much higher than that in the empty group. |
| [16] | 60 | Mandibular square hole 12 × 10 × 2 mm (length × width × depth) | PEEK-BBC composite (n = 15) |
Empty (n = 15) |
(a) no treatment (n = 15) (b) only molar groove exposition (n = 15) |
- | 4, 8, 16 | Histological analysis; RT-qPCR; Western blot | Histological analysis: low osteocytes in the empty group at each timepoint; presence of osteocytes at 4 weeks and increased number at 8 and 16 weeks in the PEEK-BBC group. RT-qPCR: BMP-2 significantly higher in the PEEK group compared with the empty group at 8 and 16 weeks. Western blot: 8 weeks: expression of BMP-2 protein significantly upregulated by the PEEK-BBC composites treatment compared with the empty group. |
| [116] | 24 | 8 mm ϕ calvarial bone defect (4 for each animal) | (a) SLP pure calcium silicate (CaSi); (b) SLP dilute Mg-doped CaSi (CaSi–Mg6); (c) DLP CaSi scaffold; (d) DLP CaSi–Mg6 |
Empty (n = 4) |
- | - | 4, 8, 12 | Histological analysis; histomorphometric analysis; micro-CT analysis | Histological and histomorphometric analyses: no inflammatory cells at 4 weeks in any group; at 12 weeks presence of mature bone with laminar structure both in CaSi and CaSi-Mg6 group; DLP CaSi group showed more new bone formation and a significant degradation of scaffold struts. Micro-CT: scaffold material decreased with time, while new bone formation increased overtime; the empty group revealed a very limited amount of bone regeneration; pure CaSi group showed limited material residual compared with the CaSi–Mg6 group, but more new bone tissue was intruded into the porous constructs of the pure CaSi scaffolds. |
| [117] | 15 | 8 mm ϕ calvarial bone defect (4 for each animal) | (a) CaP microspheres; multi-layered microspheres with layer order: (b) CaP@CaSi@CaP; (c) CaSi@CaP@CaSi |
Empty (n = 15) |
- | - | 6, 12, 18 | Histological analysis; micro-CT analysis | Histological analysis: at 6 weeks no inflammation in all groups; at 18 weeks no difference between vessel concentration in all groups; at 6 weeks multinucleate cells were observed directly just onto the surface of the CaP@CaSi@CaP microspheres. Micro-CT: empty group not healed at 18 weeks; CaSi phase was preferentially biodegraded in both the external and internal layer; Tb.N increased with the BV/TV increasing; the new bone formation started from the periphery to the center of the defect. |
| [118] | 48 | Unilateral (desumed) femoral bone defect (6.5 mm in ϕ, 6 mm in depth) | (a) 50CS/PAA (b) 65CS/PAA | Empty (n = 16) |
- | - | 4, 12 | Histological analysis | Histological analysis: small amount of newly formed bone at both 4 and 12 weeks in the empty group; 50CS/ PAA granules exhibited a slower degradation than 65CS/PAA granules. |
| [119] | 24 | Dome model (Ti barrier)—bilateral calvaria (8 mm ϕ Ti dome) | HA 60% + TCP 40% (4BoneTM) | (a) Empty (n = 12) (b) Autogenous blood (n = 12) c) DBBM (Bio-Oss®) (n = 12) |
- | - | 4, 13 | Histological analysis; histomorphometric analysis; micro-CT analysis |
Histological analysis: gap between the bone and the barrier in all groups; dense fibrous connective tissue between the titanium barrier and the bone in all groups; no sign of active bone formation in the first month, but active bone formation at 3 months; in the empty and autogenous blood groups loose connective tissue at 1 month, that mineralized at 3 months; in Bio-Oss® and test groups no material resorption was found at 1 month, while osteoclastic activity was found at 3 months. Micro-CT and histomorphometric analyses: after 1 month no statistically significant difference in bone volume augmentation among the groups; at the third month the increase in the amount of newly formed bone was statistically significant just between empty and Bio-Oss® groups. |
| [120] | 36 | Unilateral segmental radial 15-mm bone defect | (a) HA/TCP * + autogenous rBMSC (n = 6) (b) HA/TCP * + allogenic rBMSC (n = 6) (c) HA/TCP * + ovine BMSCs (n = 6) (d) HA/TCP * + canine BMSCs (n = 6) (e) cell free HA/TCP * scaffold (n = 6) |
Empty (n = 6) |
- | autologous, allogenic, ovine, canine BMSCs | 13 | Histological/histopathological analysis; radiographic evaluation (multiple time points); SEM examinations |
Histopathological analysis: average bone formation (histological score): (a) > (b) > (d) > (c) > (e) > (empty), respectively: 3.0; 2.7; 2.2; 1.9; 0.75; 0.2. Radiography: at 90 days bone formation mean values: (a) > (b) > (d) > (c) > (e) > (empty), respectively 12; 11.22; 11.20; 10.18; 06.05; 0.94. SEM: higher bone formation ad maturation, and higher scaffold degradation in group (a), followed by group (b); presence of new woven bone in the scaffold’s pores in groups (c) and (d); poor bone formation and scaffold resorption in group (e); no bone formation at the entire length of the defect in the empty group, which was filled with fibrous tissue. |
§ (n=) represents the number of sites. *calcium HA (65%) + TCP(35%); BMSCs: bone marrow-derived mesenchymal stem cells; BV/TV: bone volume/total volume; CS/PAA: calcium sulfate/poly(amino acid); DLP: double-layer printing; GFs: growth Factors; HA: hydroxyapatite; PEEK-BBC: polyether ether ketone biphasic bioceramic composite (HA and β-TCP); RT-PCR: reverse transcription quantitative polymerase chain reaction; SLP: single-layer printing; Tb.N: trabecular number; VEGF: vascular endothelial growth factor.