Allan Fernando Giovanini

Platelet-rich plasma (PRP) impairs the craniofacial bone repair associated with its elevated TGF-β levels and modulates the co-expression between collagen III and α-smooth muscle actin.

Transforming growth factor‐β (TGF‐β) is considered the main inducer of both the α‐smooth muscle actin (α‐SMA) phenotype and collagen synthesis and deposition and plays a significant role in the tissue repair and the development of fibrosis. Since the PRP constitutes an important source of TGF‐β and its efficacy on the craniofacial bone repair remains controversy, the aim of this study was to evaluate the effect of PRP in the presence of levels of TGF‐β on PRP samples, as well as in the presence of collagen III and α‐SMA+ cells, while comparing these results by means of a histomorphometric analysis of the bone matrix and fibrous deposition on the bone repair. Four bone defects of 16 mm2 were created on the calvarium of 21 rabbits. The surgical defects were treated with either particulate autograft, particulate autograft mixed with PRP and PRP alone. Animals were euthanized at 15, 30, and 45 days postoperative. Histomorphometric and immunohistochemical analyses were performed to assess repair time, as well as the expression of collagen III, and α‐SMA. The histomorphometric results demonstrated intensive deposition of fibrous tissue while hinder bone deposition occurred in PRP groups. These results coincided with higher values of the TGF‐β on the PRP sample, also larger occurrence of diffuse collagen III deposition and higher presence of α‐SMA+ cells spread among the fibrous tissue. Thus, the higher levels of TGF‐β associated with the both expression of collagen III and α‐SMA on defect treated with PRP suggest that its biomaterial induce an effect that can be considered similarly to a fibroproliferative disorder.

Platelet-rich plasma diminishes calvarial bone repair associated with alterations in collagen matrix composition and elevated CD34+ cell prevalence

The interaction between platelets and both type I and III collagens plays an important role in modulating platelet adhesion and aggregation, also contributing to the chemotaxis of CD34+ cells. The interaction with type III collagen can maintain high levels of collagen and alter the biology of bone repair when the PRP is used. The aim of this study was to evaluate the effect of platelet-rich plasma (PRP) and autograft on the presence of type III and type I collagens, the ratio between them, as well as the presence of CD34+ progenitor cells, while comparing these results by means of a histomorphometric analysis of the bone tissue. Four bone defects (8.0mm in diameter and 2.0mm in depth) were produced on the calvarium of 23 rabbits. The surgical defects were treated with either autogenous bone grafts, autogenous bone grafts with PRP and PRP alone. Animals were euthanized at 2, 4 or 6 weeks post-surgery. Histological, histomorphometric and immunohistochemical analyses were performed to assess repair time, as well as the expression of type I and III collagens, and number of progenitor CD34+ cells. Data were analyzed using the ANOVA and Student-Newman-Keuls test (alpha=5%). An enlarged granulation and medullary tissue areas in the PRP groups were observed. The use of PRP in this study hindered bone deposition, also enhanced type III to type I collagen ratio and the chemotaxis of CD34+ progenitor cells, similarly to a thrombogenic effect.

Effects of a highly concentrated platelet-rich plasma on the bone repair using non-critical defects in the calvaria of rabbits

PURPOSE To verify the effect of highly concentrated platelet-rich plasma (hPRP) in the pathways of bone repair using non-critical defects in the calvaria of rabbits. METHODS The hPRP was produced from collected venous blood of 21 rabbits. Four non-critical defects of 8 mm in diameter were created on the calvaria of each animal. The defects were all treated differently: autogenous particled bone (APB, group 1), autogenous particled bone associated with hPRP (APB + hPRP, group 2), isolated hPRP (group 3), and blood clot (control, group 4). Animals were submitted to euthanasia on the 2nd, 4th and 6th week postoperatively. Histological and histomorphometric analysis were carried through. RESULTS After two weeks, groups 1 and 2 were in more advanced stage of repair than 3 and 4. At this period, comparing the groups 1 and 2, no significant differences were found between both, which also happened between the groups 3 and 4. However, after four and six weeks, the group 1 showed a more advanced stage of repair among all the other studied groups, while group 2 was in more advanced signs of bone repair than groups 3 and 4. Comparing groups 3 and 4, after four and six weeks, the least advanced stage of bone repair was found to be within group 3. CONCLUSION The use of a highly concentrated PRP was considered prejudicial to the repair of non-critical defects in the calvaria of rabbits, either in the association of autogenous particled bone, when compared to autogenous particled bone alone, or in its isolated form, when compared to blood clot (control).

Leukocyte-Platelet-Rich Plasma (L-PRP) Induces an Abnormal Histophenotype in Craniofacial Bone Repair Associated with Changes in the Immunopositivity of the Hematopoietic Clusters of Differentiation, Osteoproteins, and TGF-β1

BACKGROUND Leukocyte-platelet-rich plasma (L-PRP) is considered an important source of growth factors, especially Transforming growth factor β 1 (TGF-β1), which modulates the proliferation and regulation of mesenchymal cells, and also exerts an influence on the hematopoiesis, osteogenesis, and adipogenesis in bone microenvironment. Thus, the aim of this study was to evaluate the effect of L-PRP on the calvarial bone repair and compare its results on the presence of TGF-β1, CD34, CD45, bone morphogenetic protein 2 (BMP2), BMPR1B, and Runx2 proteins detected by immunohistochemistry. MATERIAL AND METHODS Four bone defects were created on the calvaria of 23 rabbits. The defects were treated with autograft, L-PRP alone, and L-PRP mixed with autograft. The animals were euthanized at 2, 4, and 6 weeks post-surgery. RESULTS Unlike autograft and sham groups, the defects treated with L-PRP demonstrated significant positivity to TGF-β1, while the BMP2 was scarce. These results coincided with the lower bone matrix deposited and larger medullary area, which were composed of fibrosis, when treated with only L-PRP, or intense adiposity on defects filled with L-PRP mixed with autograft. The fibrosis that occurred was associated with a minor percentage of osteoproteins, intense presence of CD34(+) CD45(-) cells, and significant expression of TGF-β1 in all time periods analyzed. The adiposity occurred from the major presence of osteoprogenitor BMPR1B (+) Runx2(+) cells simultaneously to BMP2(-) TGF-β1(+) and CD34(+) CD45(+/-) expressions predominantly on the earlier period. CONCLUSION From this study, it can be concluded that the L-PRP used alone or mixed to autograft hindered the osteoneogenesis due to suppression of immunoexpression of BMP2, while the immunopositivity of TGF-β1 was intense. When used alone, the L-PRP induced a fibrotic condition associated with TGF-β1 presence and lack of osteoproteins, but when L-PRP was mixed to autograft, it induced the presence of the osteolineage cells (BMPR1B (+) Runx2(+) ), but also inhibited the terminal osteoblastic maturation associated with the lack of BMP2 and the presence of TGF-β1(+) , a fact that contributed to cellular transdifferentiation into fat cells.

Neoplasias astrocitárias e correlação com as proteínas p53 mutada e Ki-67

The astrocytic neoplasms respond by 60% of the central nervous system tumors, being the study of the molecular biology an important step for the understanding of the genesis and biological behavior of these diseases. The Ki-67 proteins, which are markers of the cellular proliferation, and p53, which is the product of the tumor suppressor gene TP53, are both important tumoral markers. This study intends to identify and quantify the Ki-67 and p53 proteins in astrocytic tumors of different grades of malignancy, as well as to analyze their relations with age and gender. Ki-67 and p53 proteins in 47 patients with surgically resected astrocytic neoplasms were studied through immunohistochemistry. They have been previously classified and reviewed concerning their histological grade, as suggested by the World Health Organization. The immunomarked cellular nuclei were quantified by the program Imagelab-softium for the absolute parametric reason between the nuclei of the positive cells and the total amount of tumoral cells, being counted 1000 cells. The lineation used has been transversal not controlled. For the statistical analysis the variables were divided into groups. For the Ki-67 they were absent, <5% and >5% and for p53 they were absent (0), <25% (1+), between 25 and 50% (2+), between 50 and 75% (3+), and higher than 75% (4+). Ki-67 was present in 37 cases (78.72%) evidencing a correlation with a higher malignancy degree (p<0,001). p53 was present in 14 cases (35.13%) with a higher correlation with astrocytoma grade IV (p=0.59). There has not been a statistically significant correlation between p53 and Ki-67, as well as among these variables, age and gender. The hypotheses of a greater presence of Ki-67 and p53 in astrocytic neoplasms with a higher degree of malignancy, except for the correlation between grade III and p53, is corroborated by the results of this study.

Fragmented adipose tissue graft for bone healing: histological and histometric study in rabbits' calvaria

Objective The adipose tissue represents an important reservoir of stem cells. There are few studies in the literature with which to histologically evaluate whether or not the adipose tissue graft is really a safe option to achieve bone repair. This study histologically analyzed the effect of fragmented autogenous adipose tissue grafts on bone healing in surgically created, critical-size defects (CSD) in a rabbit’s calvaria. Study design Forty-two New Zealand rabbits were used in this study. CSD that were 15 mm in diameter were created in the calvarium of each animal. The defects were randomly divided into two groups: in Group C (control), the defect was filled only by a blood clot and, in Group FAT (i.e., fragmented adipose tissue), the defect was filled with fragmented autogenous adipose tissue grafts. The groups were divided into subgroups (n = 7) for euthanasia at 7, 15, and 40 days after the procedure had been conducted. Histologic and histometric analyses were performed. Data were statistically analysed with ANOVA and Tukey’s tests (p < 0.05). Results The amount of bone formation did not show statistically significant differences seven days after the operation, which indicates that the groups had similar amounts of mineral deposition in the earlier period of the repair. Conversely, a significant of amount of bone matrix deposition was identified in the FAT group at 15 and 40 days following the operation, both on the border and in the body of the defect. Such an outcome was not found in the control group. Conclusion In this study, an autologous adipose tissue graft may be considered as likely biomaterial for bone regeneration, since it positively affected the amount of bone formation in surgically created CSD in the rabbits’ calvaria 40 days after the procedure had been performed. Further investigations with a longer time evaluation are warranted to determine the effectiveness of autologous adipose tissue graft in the bone healing. Key words:Adipose tissue, bone regeneration, rabbits, critical defects.

Nonprocessed adipose tissue graft in the treatment of dehiscence bone defects in rabbit tibiae: a pilot study.

Objective:To evaluate the bone repair of surgically created dehiscence-type defects (3 × 5 mm) around dental implants in rabbit tibia using nonprocessed adipose tissue graft or autogenous bone graft. Materials and Methods:The bone defects were randomly assigned to 3 groups: blood clot (C), autogenous bone (AB), and nonprocessed adipose tissue (AT). After 3 months, the animals were euthanized. Histomorphometric analyses were performed, and the results were analyzed with analysis of variance and Tukey tests (P ⩽ 0.05). Statistics were performed for the percentage of the bone-to-implant contact (BIC) and bone area (BA) within the limits of the threads. Results:The results for BIC in the AT (37.75% ± 28.03%) and C (40.57 ± 13.71%) groups were statistically similar, whereas the AB group had the greatest percentage of BIC (83.37% ± 11.85%). For all groups, the BA percentage was similar (61.48% ± 30.89% in AT; 72.90% ± 14.10% in C; 84.23% ± 11.96% in AB), with no statistically significant differences. Conclusion:Nonprocessed adipose tissue is not a comparable substitute for autogenous bone in the treatment of dehiscence bone defects around titanium dental implants.

Radiographic and histological evaluation of ectopic application of deproteinized bovine bone matrix.

Objective: To evaluate, through radiographic and histological analysis, the tissue reaction induced by a biomaterial based on deproteinized bovine bone matrix (DBBM) in the muscle of sheep. sMaterials and Methods: Sixteen sheep were used. The animals underwent surgery to insert polyethylene tubes containing the biomaterial in the muscle of the lower back (ectopic site) and were euthanized after 3 and 6 months. Each sheep received three tubes: Group 1 - sham group (negative control - tube without biomaterial), Group 2 - particulate autogenous bone (positive control), and Group 3 - DBBM biomaterial (GenOx Inorg). The material removed was evaluated by radiographic, macroscopic, and microscopic analysis, descriptively. Results: Macroscopic analysis showed that Group 3 had a greater tissue volume maintenance. Microscopic analysis indicated that Group 1 had a higher concentration of dense, thin collagen fibers (3 and 6 months); in Group 2, there was a decrease in the inflammatory process and the deposition of dense, thin collagen fibers (3 and 6 months); in Group 3, the presence of a dense connective tissue was noted, in which the DBBM particles (3 months) were found. On the periphery of these particles, a deposition of basophilic material was found, indicating the formation of mineral particles and the formation of tissues with osteoid characteristics (6 months). Conclusion: Based on the results obtained, it can be concluded that the biomaterial based on DBBM led to the formation of tissue with similar characteristics to an osteoid matrix in a postoperative period of 6 months. However, none of the groups evaluated showed ectopic bone neoformation.

Primary mandibular xanthoma: case report

Xanthoma is a very rare bone tumor, especially in the mandible, that can be associated with metabolic diseases such as hyperlipidemia. A 14-year-old girl presented with a non-corticated unilocular radiolucent lesion observed on panoramic radiography. The lesion was located between the roots of the left first and second premolar teeth, extending from the cervical to the apical region, measuring approximately 1 cm in greatest dimension. An excisional biopsy revealed foam cells and occasional nonfoamy mononuclear macrophage-like cells spread among a discrete fibrous stroma. Immunohistochemically, the xanthomatous cells were CD68 and vimentin positive, focally positive for S100, CD1a, and CD3 and negative for AE1/AE3, CD20, CD117, and HMB45. Hematologic and biochemical investigations ruled out systemic disease.

Leukocyte-platelet-rich plasma diminishes bone matrix deposition in rat calvaria treated with autograft due to simultaneous increase in immunohistochemical expression of Indian Hedgehog, transforming growth factor-β, and parathyroid-1 receptor

PURPOSE This study evaluated the immunohistochemical presence of Indian Hedgehog (IHH), transforming growth factor-β (TGF-β), and parathyroid-1 receptor (PTH1R) in calvaria bone repair, and compared these results with the histological bone matrix features in defects treated with autograft in the presence or absence of L-PRP. MATERIAL AND METHODS An artificial bone defect measuring 5 × 1 mm was produced in the calvaria of 28 Wistar rats. Randomly the defects were treated with autograft and autograft mixed with L-PRP. The animals were euthanized at 15 and 40 days post-surgery. Data were analyzed by Student-Newman-Keuls test (p ≤ .05) for immunohistochemical interpretation. RESULTS The results revealed that the histological characteristic of bone matrix deposited in the defect was different in the defects treated with L-PRP. The group that received only the autograft demonstrated larger haversian bone matrix deposited, whereas the group that received autograft mixed with L-PRP revealed trabecular bone deposition. These results coincided with significantly higher immunopositivity for IHH, TGF-β1, and PTH1R in the L-PRP group. CONCLUSION These results suggest that L-PRP altered the biological characteristic of the autograft, increasing the bone cells IHH+ but inducing a trabecular bone associated with intense quantities of TGF-β and PTH1R.