Biological evaluation of critical bone defect regeneration using hydroxyapatite/ alginate composite granules.

PURPOSE: to evaluate biocompatibility and osteogenic potential of hydroxyapatite/alginate composite after its implantation on rat calvarian critical bone defect. METHODS: thirty adults male Wistar rats were randomly distributed into two groups: GHA - critical bone defect filled with hydroxyapatite/alginate composite granules (HA/Alg) and CG - critical bone defect without biomaterial; evaluated at biological points of 15, 45 and 120 days. RESULTS: the histomorphometrically analyses for GHA showed osteoid matrix deposition (OM) among the granules and towards the center of the defect in centripetal direction throughout the study, with evident new bone formation at 120 days, resulting in filling 4/5 of the initial bone defect. For CG, this finding was restricted to the edges of the bone margins and formation of connective tissue on the residual area was found in all biological points. Inflammatory response on GHA was chronic granulomatous type, discrete and regressive for all biological points. Throughout the study, the CG presented mononuclear inflammatory infiltrate diffuse and regressive. Histomorphometry analyses showed that OM percentage was evident for GHA group when compared to CG group in all analyzed periods (p > 0.05). CONCLUSIONS: the biomaterial evaluated at this study showed to be biocompatible, bioactive, osteoconductive and biodegradable synchronously with bone formation.

Biological evaluation of critical bone defect regeneration using hydroxyapatite/ alginate composite granules

Purpose: to evaluate biocompatibility and osteogenic potential of hydroxyapatite/alginate composite after its implantation on rat calvarian critical bone defect. Methods: thirty adults male Wistar rats were randomly distributed into two groups: GHA ­ critical bone defect filled with hydroxyapatite/alginate composite granules (HA/Alg) and CG ­ critical bone defect without biomaterial; evaluated at biological points of 15, 45 and 120 days. Results: the histomorphometrically analyses for GHA showed osteoid matrix deposition (OM) among the granules and towards the center of the defect in centripetal direction throughout the study, with evident new bone formation at 120 days, resulting in filling 4/5 of the initial bone defect. For CG, this finding was restricted to the edges of the bone margins and formation of connective tissue on the residual area was found in all biological points. Inflammatory response on GHA was chronic granulomatous type, discrete and regressive for all biological points. Throughout the study, the CG presented mononuclear inflammatory infiltrate diffuse and regressive. Histomorphometry analyses showed that OM percentage was evident for GHA group when compared to CG group in all analyzed periods (p > 0.05). Conclusions: the biomaterial evaluated at this study showed to be biocompatible, bioactive, osteoconductive and biodegradable synchronously with bone formation.

Comparative Analysis of the Effect of Two Therapeutic Ultrasound Protocols for Regeneration of a Critical Bone Defect.

Objective To compare the effect of two therapeutic ultrasound protocols, with different times of exposure in the regeneration of critical bone defect. Methods Forty-five male rats were distributed among three experimental groups: therapeutic ultrasound group 5 minutes (TUG 5); therapeutic ultrasound group 10 minutes (TUG 10); and control group (CG). In all groups, a critical bone defect of 8.5 mm diameter was made in the calvaria region. The protocol was initiated on the 1 st postoperative day in TUGs 5 and 10, with therapeutic ultrasound at the frequency of 1.0 MHz, pulsed mode, five times a week, at periods of 15, 30, and 60 days. Results Among the experimental groups, the highest volume of neoformation of osteoid matrix took place in the TUG 10 group followed by TUG 5, when compared with the CG group, in which the neoformation was restricted to the border region. The use of ultrasound promoted an increase in the thickness of the conjunctive matrix, proliferation of capillaries, alignment of the collagen fibers, reduction of edema and inflammatory process, being more significant in the 10-minutes time period. Conclusion Therapeutic ultrasound stimulated the repair of a critical bone defect, and the longer exposure time promoted greater osteogenic stimulation.

Comparative Analysis of the Effect of Two Therapeutic Ultrasound Protocols for Regeneration of a Critical Bone Defect / Análise comparativa do efeito de dois protocolos de ultrassom terapêutico para regeneração de defeito ósseo crítico

Abstract Objective To compare the effect of two therapeutic ultrasound protocols, with different times of exposure in the regeneration of critical bone defect. Methods Forty-five male rats were distributed among three experimental groups: therapeutic ultrasound group 5 minutes (TUG 5); therapeutic ultrasound group 10 minutes (TUG 10); and control group (CG). In all groups, a critical bone defect of 8.5 mm diameter was made in the calvaria region. The protocol was initiated on the 1st postoperative day in TUGs 5 and 10, with therapeutic ultrasound at the frequency of 1.0 MHz, pulsed mode, five times a week, at periods of 15, 30, and 60 days. Results Among the experimental groups, the highest volume of neoformation of osteoid matrix took place in the TUG 10 group followed by TUG 5, when compared with the CG group, in which the neoformation was restricted to the border region. The use of ultrasound promoted an increase in the thickness of the conjunctive matrix, proliferation of capillaries, alignment of the collagen fibers, reduction of edema and inflammatory process, being more significant in the 10-minutes time period. Conclusion Therapeutic ultrasound stimulated the repair of a critical bone defect, and the longer exposure time promoted greater osteogenic stimulation.

Resumo Objetivo Comparar o efeito de dois protocolos de ultrassom terapêutico com diferentes tempos de exposição para regeneração de defeito ósseo crítico. Métodos Foram utilizados 45 ratos, machos, distribuídos em três grupos: grupo ultrassom terapêutico 5 minutos (GUS 5); grupo ultrassom terapêutico 10 minutos (GUS 10); e grupo controle (GC). Em todos os grupos, confeccionou-se um defeito ósseo crítico, com 8,5 mm de diâmetro, na região da calvária. O protocolo foi iniciado no 1º dia do pós-operatório, no GUS 5 e no GUS 10, com ultrassom terapêutico na frequência de 1,0 MHz, modo pulsado, 5 vezes por semana, nos períodos de 15, 30, e 60 dias. Resultados Dentre os grupos experimentais, houve maior neoformação de matriz osteoide no GUS 10, seguido do GUS 5 quando comparados ao GC, no qual a neoformação foi restrita à região de borda. O uso do ultrassom promoveu aumento na espessura da matriz conjuntiva, proliferação de capilares, alinhamento das fibras colágenas, redução do edema e do processo inflamatório, tendo sido mais significativo no tempo de 10 minutos. Conclusão O ultrassom terapêutico estimulou o reparo do defeito ósseo crítico, e o maior tempo de exposição promoveu maior estímulo osteogênico.

Influence of the geometry of nanostructured hydroxyapatite and alginate composites in the initial phase of bone repair1.

PURPOSE: To analyze, histomorphologically, the influence of the geometry of nanostructured hydroxyapatite and alginate (HAn/Alg) composites in the initial phase of the bone repair. METHODS: Fifteen rats were distributed to three groups: MiHA - bone defect filled with HAn/Alg microspheres; GrHA - bone defect filled with HAn/Alg granules; and DV - empty bone defect; evaluated after 15 days postoperatively. The experimental surgical model was the critical bone defect, ≅8.5 mm, in rat calvaria. After euthanasia the specimens were embedded in paraffin and stained with hematoxylin and eosin, picrosirius and Masson-Goldner's trichrome. RESULTS: The histomorphologic analysis showed, in the MiHA, deposition of osteoid matrix within some microspheres and circumjacent to the others, near the bone edges. In GrHA, the deposition of this matrix was scarce inside and adjacent to the granules. In these two groups, chronic granulomatous inflammation was noted, more evident in GrHA. In the DV, it was observed bone neoformation restricted to the bone edges and formation of connective tissue with reduced thickness in relation to the bone edges, throughout the defect. CONCLUSION: The geometry of the biomaterials was determinant in the tissue response, since the microspheres showed more favorable to the bone regeneration in relation to the granules.

Influence of the geometry of nanostructured hydroxyapatite and alginate composites in the initial phase of bone repair

Abstract Purpose: To analyze, histomorphologically, the influence of the geometry of nanostructured hydroxyapatite and alginate (HAn/Alg) composites in the initial phase of the bone repair. Methods: Fifteen rats were distributed to three groups: MiHA - bone defect filled with HAn/Alg microspheres; GrHA - bone defect filled with HAn/Alg granules; and DV - empty bone defect; evaluated after 15 days postoperatively. The experimental surgical model was the critical bone defect, ≅8.5 mm, in rat calvaria. After euthanasia the specimens were embedded in paraffin and stained with hematoxylin and eosin, picrosirius and Masson-Goldner's trichrome. Results: The histomorphologic analysis showed, in the MiHA, deposition of osteoid matrix within some microspheres and circumjacent to the others, near the bone edges. In GrHA, the deposition of this matrix was scarce inside and adjacent to the granules. In these two groups, chronic granulomatous inflammation was noted, more evident in GrHA. In the DV, it was observed bone neoformation restricted to the bone edges and formation of connective tissue with reduced thickness in relation to the bone edges, throughout the defect. Conclusion: The geometry of the biomaterials was determinant in the tissue response, since the microspheres showed more favorable to the bone regeneration in relation to the granules.

Cytokines and soluble HLA-G levels in bone marrow stroma and their association with the survival rate of patients exhibiting childhood T-cell acute lymphoblastic leukemia.

Leukemic cells can induce defective expression of soluble factors and change marrow cytokine profile, leading to aberrant cell signaling, cell fixation and cell proliferation in bone marrow. T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disorder which accounts for 15% of pediatric ALL. To evaluate the contribution of immunological factors on T-ALL survival, we measured Th1, Th2, Th17 cytokines and soluble HLA-G (sHLA-G) levels in bone marrow from 32 Brazilian children at diagnosis (D0), after induction (D19) and after consolidation (D49) of the chemotherapy phase. Data were analyzed using non-parametric tests, and survival rates were evaluated by Kaplan-Meier method (log-rank test). TNF, IL-10 and IL-6 levels were increased at diagnosis compared to D19 and D49. IL-10 levels<4.57pg/mL at diagnosis were associated with increased survival rate, in presence of positive correlation between IL-2 and IL-17 levels. Increased survival rate was also associated with IFN-γ levels<1.17pg/mL at D49, with a positive correlation observed between IL-4 and IL-2 as well IL-4 and IL-17 levels. In contrast, worse survival rate was associated with IL-2, IL-4 and IL-10 levels imbalance. In addition, increased sHLA-G levels at diagnosis were associated with increased leukocyte count, a well-known factor for poor prognosis. In conclusion, cytokines and sHLA-G play an essential role in marrow T-ALL microenvironment during chemotherapy, especially the immunosuppressive cytokine IL-10 which can be used as biomarker of disease outcome, being also a potential target for novel T-ALL treatments.