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Regeneration of large bone defects is a major objective in trauma surgery. Bone marrow mononuclear cell (BMC)-supported bone healing was shown to be efficient after immobilization on a scaffold. We hypothesized that fibrous demineralized bone matrix (DBM) in various forms with BMCs is superior to granular DBM. A total of 65 male SD rats were assigned to five treatment groups: syngenic cancellous bone (SCB), fibrous demineralized bone matrix (f-DBM), fibrous demineralized bone matrix densely packed (f-DBM 120%), DBM granules (GDBM) and DBM granules 5% calcium phosphate (GDBM5%Ca2+). BMCs from donor rats were combined with different scaffolds and placed into 5 mm femoral bone defects. After 8 weeks, bone mineral density (BMD), biomechanical stability and histology were assessed. Similar biomechanical properties of f-DBM and SCB defects were observed. Similar bone and cartilage formation was found in all groups, but a significantly bigger residual defect size was found in GDBM. High bone healing scores were found in f-DBM (25) and SCB (25). The application of DBM in fiber form combined with the application of BMCs shows promising results comparable to the gold standard, syngenic cancellous bone. Denser packing of fibers or higher amount of calcium phosphate has no positive effect.
The Masquelet technique for the treatment of large bone defects is a two-stage procedure based on an induced membrane. We eliminate the first surgical step by using a decellularized dermal skin graft (Epiflex®) populated with bone marrow mononuclear cells (BMC), as a replacement for the induced membrane. The aim of this study was to demonstrate the feasibility of this technology and provide evidence of equivalent bone healing in comparison to the induced membrane-technique. Therefore, 112 male Sprague–Dawley rats were allocated in six groups and received a 10 mm femoral defect. Defects were treated with either the induced membrane or decellularized dermis, with or without the addition of BMC. Defects were then filled with a scaffold (β-TCP), with or without BMC. After a healing time of eight weeks, femurs were taken for histological, radiological and biomechanical analysis. Defects treated with Epiflex® showed increased mineralization and bone formation predominantly in the transplanted dermis surrounding the defect. No significant decrease of biomechanical properties was found. Vascularization of the defect could be enhanced by addition of BMC. Considering the dramatic reduction of a patient’s burden by the reduced surgical stress and shortened time of treatment, this technique could have a great impact on clinical practice.
The Masquelet technique is used to treat large bone defects; it is a two-stage procedure based on an induced membrane. To improve the induced membrane process, demineralized bone matrix in granular (GDBM) and fibrous form (f-DBM) was tested with and without bone marrow mononuclear cells (BMC) as filling of the membrane against the gold standard filling with syngeneic cancellous bone (SCB). A total of 65 male Sprague–Dawley rats obtained a 5 mm femoral defect. These defects were treated with the induced membrane technique and filled with SCB, GDBM, or f-DBM, with or without BMC. After a healing period of eight weeks, the femurs were harvested and submitted for histological, radiological, and biomechanical analyses. The fracture load in the defect zone was lower compared to SCB in all groups. However, histological analysis showed comparable new bone formation, bone mineral density, and cartilage proportions and vascularization. The results suggest that f-DBM in combination with BMC and the induced membrane technique cannot reproduce the very good results of this material in large, non-membrane coated bone defects, nevertheless it supports the maturation of new bone tissue locally. It can be concluded that BMC should be applied in lower doses and inflammatory cells should be removed from the cell preparation before implantation.
Introduction: The induced membrane technique for the treatment of large bone defects is a two-step procedure. In the first operation, a foreign body membrane is induced around a spacer, then, in the second step, several weeks or months later, the spacer is removed and the Membrane pocket is filled with autologous bone material. Induction of a functional biological membrane might be avoided by initially using a biological membrane. In this study, the effect of a human acellular dermis (hADM, Epiflex, DIZG gGmbH) was evaluated for the treatment of a large (5 mm), plate-stabilised femoral bone defect.
Material and Methods: In an established rat model, hADM was compared to the two-stage induced membrane technique and a bone defect without membrane cover. Syngeneous spongiosa from donor animals was used for defect filling in all groups. The group size in each case was n = 5, the induction time of the membrane was 3–4 weeks and the healing time after filling of the defect was 8 weeks.
Results: The ultimate loads were increased to levels comparable with native bone in both membrane groups (hADM: 63.2% ± 29.6% of the reference bone, p < 0.05 vs. no membrane, induced membrane: 52.1% ± 25.8% of the reference bone, p < 0.05 vs. no membrane) and were significantly higher than the control group without membrane (21.5%). The membrane groups were radiologically and histologically almost completely bridged by new bone formation, in contrast to the control Group where no closed osseous bridging could be observed.
Conclusion: The use of the human acellular dermis leads to equivalent healing results in comparison to the two-stage induced membrane technique. This could lead to a shortened therapy duration of large bone defects.
Determination of the effective dose of bone marrow mononuclear cell therapy for bone healing in vivo
(2020)
Introduction: Cell-based therapy by bone marrow mononuclear cells (BMC) in a large-sized bone defect has already shown improved vascularization and new bone formation. First clinical trials are already being conducted. BMC were isolated from bone marrow aspirate and given back to patients in combination with a scaffold within some hours. However, the optimal concentration of BMC has not yet been determined for bone healing. With this study, we want to determine the optimal dosage of the BMC in the bone defect to support bone healing.
Material and methods: Scaffolds with increasing BMC concentrations were inserted into a 5 mm femoral defect, cell concentrations of 2 × 106 BMC/mL, 1 × 107 BMC/mL and 2 × 107 BMC/mL were used. Based on the initial cell number used to colonize the scaffolds, the groups are designated 1 × 106, 5 × 106 and 1 × 107 group. Bone healing was assessed biomechanically, radiologically (µCT), and histologically after 8 weeks healing time.
Results: Improved bone healing parameters were noted in the 1 × 106 and 5 × 106 BMC groups. A significantly higher BMD was observed in the 1 × 106 BMC group compared to the other groups. Histologically, a significantly increased bone growth in the defect area was observed in group 5 × 106 BMC. This finding could be supported radiologically.
Conclusion: It was shown that the effective dose of BMC for bone defect healing ranges from 2 × 106 BMC/mL to 1 × 107 BMC/mL. This concentration range seems to be the therapeutic window for BMC-supported therapy of large bone defects. However, further studies are necessary to clarify the exact BMC-dose dependent mechanisms of bone defect healing and to determine the therapeutically effective range more precisely.
The Masquelet technique for the treatment of large bone defects is a two‐stage procedure based on an induced membrane. The size of a scaffold is reported to be a critical factor for bone healing response. We therefore aimed to investigate the influence of the granule size of a bone graft substitute on bone marrow derived mononuclear cells (BMC) supported bone healing in combination with the induced membrane. We compared three different sizes of Herafill® granules (Heraeus Medical GmbH, Wehrheim) with or without BMC in vivo in a rat femoral critical size defect. A 10 mm defect was made in 126 rats and a membrane induced by a PMMA‐spacer. After 3 weeks, the spacer was taken out and membrane filled with different granule sizes. After 8 weeks femurs were taken for radiological, biomechanical, histological, and immunohistochemical analysis. Further, whole blood of the rat was incubated with granules and expression of 29 peptide mediators was assessed. Smallest granules showed significantly improved bone healing compared to larger granules, which however did not lead to an increased biomechanical stability in the defect zone. Small granules lead to an increased accumulation of macrophages in situ which could be assigned to the inflammatory subtype M1 by majority. Increased release of chemotactic respectively proangiogenic active factors in vitro compared to syngenic bone and beta‐TCP was observed. Granule size of the bone graft substitute Herafill® has significant impact on bone healing of a critical size defect in combination with Masquelet's technique in terms of bone formation and inflammatory.