The effect of L-PRF membranes on bone healing in rabbit tibiae bone defects: micro-CT and biomarker results

Non-contact electrical stimulation via a Vector-potential transformer promotes bone healing in drill-hole injury model

INTRODUCTION

We investigated the effects of non-contact electrical stimulation via a Vector-potential (VP) transformer, a novel physical therapy device, on bone healing in drill-hole injury models.

MATERIALS AND METHODS

Six-week-old male Wistar rats, after a one-week acclimation period, were divided into three groups: the control group (CO), the bone injury group (BI), in which a drill-hole injury was created, and the VP stimulation group (VP), which received non-contact electrical stimulation via a VP transformer after bone injury. In the VP group, rats underwent stimulation at 200 kHz for 30 minutes per day, seven days per week.

RESULTS

The VP group exhibited increased bone formation as early as day 7 post-injury, with significantly higher bone volume than the BI group at all time points (day 7: p = 0.0003; day 14: p = 0.0024; day 21: p = 0.0001). By day 21, the VP group showed lighter toluidine blue staining and reduced biglycan immunoreactivity compared to the BI group. Bone mineral density also increased (p = 0.0008). Osteoblasts in the VP group displayed abundant cytoplasm and a high capacity for osteocalcin synthesis. Additionally, the VP group demonstrated increased expression of Bglap (day 5: p = 0.0068; day 7: p = 0.0096) and Ctsk (day 7: p = 0.0329; day 14: p = 0.0171), along with a higher number of TRAP-positive osteoclasts (day 21: p = 0.0159) compared to the BI group.

CONCLUSION

Non-contact electrical stimulation via a VP transformer promotes bone healing in drill-hole injury models.

Molecular insights into the proteomic composition of porcine treated dentin matrix

Background

Human-treated dentin matrix (hTDM) has recently been studied as a natural extracellular matrix-based biomaterial for dentin pulp regeneration. However, porcine-treated dentin matrix (pTDM) is a potential alternative scaffold due to limited availability. However, there is a dearth of information regarding the protein composition and underlying molecular mechanisms of pTDM.Methods: hTDM and pTDM were fabricated using human and porcine teeth, respectively, and their morphological characteristics were examined using scanning electron microscopy. Stem cells derived from human exfoliated deciduous teeth (SHEDs) were isolated and characterized using flow cytometry and multilineage differentiation assays. SHEDs were cultured in three-dimensional environments with hTDM, pTDM, or biphasic hydroxyapatite/tricalcium phosphate. The expression of odontogenesis markers in SHEDs were assessed using real-time polymerase chain reaction and immunochemical staining. Subsequently, SHEDs/TDM and SHEDs/HA/TCP complexes were transplanted subcutaneously into nude mice. The protein composition of pTDM was analyzed using proteomics and compared to previously published data on hTDM.Results: pTDM and hTDM elicited comparable upregulation of odontogenesis-related genes and proteins in SHEDs. Furthermore, both demonstrated the capacity to stimulate root-related tissue regeneration in vivo. Proteomic analysis revealed the presence of 278 protein groups in pTDM, with collagens being the most abundant. Additionally, pTDM and hTDM shared 58 identical proteins, which may contribute to their similar abilities to induce odontogenesis.

Conclusions

Both hTDM and pTDM exhibit comparable capabilities in inducing odontogenesis, potentially owing to their distinctive bioactive molecular networks.

Efficacy of photobiomodulation using diode laser 650 nm combined with nano-cellulose and nano-amorphous calcium phosphate in bone healing of rabbit tibial defects assessed by H&E staining and computed tomography

BACKGROUND

The purpose of the current study was to evaluate the effect of Diode LLLT 650 nm, TEMPO oxidized Nano-fibrillated cellulose mixed with Nano-Amorphous calcium phosphate, and their combination on bone healing in rabbit tibia using H&E staining and computed tomography.

METHODS

Eighteen adult male New Zealand rabbits were selected, two circular bone defects were created in each tibia, resulting in four bony defects in each rabbit, representing the four tested groups; group A (negative control), group B (filled with mineralized nano-cellulose), group C (combination), group D (laser). Animals were euthanized after two weeks and one month, defects were assessed by CT for bone density, then histological samples were examined by H&E stain.

RESULTS

In both evaluation periods, group D recorded the greatest mean area percent of new bone formation and bone density, followed by group A, while group C recorded the lowest value. Groups A and D showed full closure of the defects, while groups B and C showed partial defect closure with retained bone graft material. H&E and CT showed that Laser group had the best results of defects healing, bone density and new bone formation, followed by the negative control group.

CONCLUSIONS

Diode laser 650nm photobiomodulation significantly improved bone defects healing. Mineralized nano-cellulose experimental bone substitute material showed a delayed effect in bone healing and graft material resorption. The combination of LLLT with the graft material had no positive outcome on bone defect healing.

The effects of allogeneic and xenogeneic lyophilized leukocyte-and platelet-rich fibrin on bone healing in rat

BACKGROUND

Critical size defects are one of the challenges in the treatment of fractures in humans and animals. Blood products such as leukocyte-SAand platelet-rich fibrin (L-PRF) are one of the alternatives to bone autograft to solve this challenge. This study aims to evaluate the effects of allogeneic and xenogeneic lyophilized L-PRF on bone healing in a critical defect of radius bone in rat.

METHODS

A defect with a diameter of 5 mm was created in the radius bone of 60 rats in four groups. The defect was left empty in the untreated group, and it was filled with autogenous bone graft, allogeneic, and xenogeneic lyophilized L-PRF, respectively, in the other three groups. Radiographic evaluation was done every two weeks, and histopathological evaluation in the 14th, 28th, and 56th days after surgery.

RESULTS

The radiographic scores of allogeneic and xenogeneic lyophilized l-PRF groups were significantly higher than the untreated group in all times (P<0.05). In connection with histopathological Emery's scoring system, the score of allogeneic lyophilized L-PRF was significantly higher than the untreated group (P<0.05) in the 14th and 28th days after surgery. The score of the xenogeneic lyophilized L-PRF group was also higher than the untreated group, but the difference was not significant (P>0.05). The allogeneic and xenogeneic lyophilized L-PRF scores were significantly higher than the untreated group (P < 0.05) on the 56th day.

CONCLUSION

The results of the present study showed that the allogeneic and xenogeneic lyophilized L-PRF can improve bone healing in the critical radius bone defect in rat model of study.

Reinforcement of colon anastomosis healing with leukocyte platelet-rich fibrin in rabbit model

AIM

This study investigated the regenerative efficacy of leukocyte platelet-rich fibrin (L-PRF) on colon anastomotic healing in rabbits.

MAIN METHODS

Thirty-six healthy male white New Zealand rabbits were subjected to complete transactions of the ascending colon. The rabbits were equally divided into two groups: the control group, where the transected colon ends were anastomosed by a simple interrupted suture pattern, and the L-PRF-treated group, in which L-PRF was wrapped entirely around the anastomotic line. The postoperative acute pain scale was assessed using the Bristol Rabbit Pain Scale before surgery and at each four-hour interval post-operatively. After euthanizing the rabbits, the adhesion degree score, anastomotic bursting pressure, and stenosis degree of the anastomotic colon were assessed, and histopathological examination at the 7th, 14th, and 28th days postoperatively.

KEY FINDINGS

Rabbits in both groups showed a significant increase in pain scores compared to baseline. Postoperatively, the L-PRF group exhibited significantly lower pain scores, adhesion scores, and stenosis degrees than the control group. However, the anastomotic bursting pressure was significantly higher in the L-PRF group. Re-epithelialization, polymorphonuclear neutrophil infiltration, granulation tissue formation, and collagen deposition scores were improved considerably in the L-PRF group compared to the control group. Immunostaining of growth factor expression was significantly lower in the control than in the L-PRF group.

SIGNIFICANCE

The L-PRF can augment collagen deposition, re-epithelialize the mucosa, promote angiogenesis, reduce adhesions, and diminish the stenosis degree scores. Therefore, it can be considered a promising aid in healing bowel anastomoses.

Evaluation of the osteoconductivity and the degradation of novel hydroxyapatite/polyurethane combined with mesoporous silica microspheres in a rabbit osteomyelitis model

Bone defects caused by osteomyelitis can lead to severe disability. Surgeons still face significant challenges in treating bone defects. Nano-hydroxyapatite (n-HA) plays an important role in bone tissue engineering due to its excellent biocompatibility and osteoconductivity. Levofloxacin (Levo) was encapsulated in mesoporous silica nanoparticles (MSNs) via electrostatic attraction to serve as a drug delivery system. MSNs were incorporated with n-HA and polyurethane (PU). The degradation and osteoconductivity properties of these novel composite scaffolds and their effectiveness in treating chronic osteomyelitis in a rabbit model were assessed. Gross pathology, radiographic imaging, micro-computed tomography, Van Gieson staining, and hematoxylin and eosin staining were conducted at 6 and 12 weeks. The group of composite scaffolds combining n-HA/PU with MSNs containing 5 mg Levo (n-HA/PU + Nano +5 mg Levo) composite scaffolds showed superior antibacterial properties compared to the other groups. At 12 weeks, the n-HA/PU + Nano +5 mg Levo composite scaffolds group exhibited significantly greater volume of new trabecular bone formation compared to the other three groups. The surface of the novel composite scaffolds exhibited degradation after 6 weeks implantation. The internal structure of the scaffolds collapsed noticeably after 12 weeks of implantation. The rate of material degradation corresponded to the rate of new bone ingrowth. This novel composite scaffold, which is biodegradable and osteoconductive, has potential as a drug delivery system for treating chronic osteomyelitis accompanied by bone defects.

Morphologic analysis of the 1st and 2nd tarsometatarsal joint articular surfaces

Tarsometatarsal joint arthrodesis is used to treat a variety of injuries and deformities in the midfoot. However, the surgical technique has not been optimized, in part due to limited knowledge of morphologic features and variation in the related joints. Previous research has relied primarily on dissection-based anatomical analysis, but quantitative imaging may allow for a more sophisticated description of this complex. Here, we used quantitative micro-CT imaging to examine dimensions, distance maps, and curvature of the four articular surfaces in the first and second tarsometatarsal joints. Image segmentation, articular surface identification, and anatomic coordinate systems were all done with semi or fully automatic methods, and distance and size measurements were all taken utilizing these anatomic planes. Surface curvature was studied using Gaussian curvature and a newly defined measure of curvature similarity on the whole joint and on four subregions of each surface. These data show larger articular surfaces on the cuneiforms, rather than metatarsals, and define the generally tall and narrow articular surfaces seen in these joints. Curvature analysis shows minimally curved opposing convex surfaces. Our results are valuable for furthering knowledge of surgical anatomy in this poorly understood region of the foot.

In vitro and in vivo assessment of decellularized platelet-rich fibrin-loaded strontium doped porous magnesium phosphate scaffolds in bone regeneration

The present work reports the effect of decellularized platelet-rich fibrin (dPRF) loaded strontium (Sr) doped porous magnesium phosphate (MgP) bioceramics on biocompatibility, biodegradability, and bone regeneration. Sustained release of growth factors from dPRF is a major objective here, which conformed to the availability of dPRF on the scaffold surface even after 7 days of in vitro degradation. dPRF-incorporated MgP scaffolds were implanted in the rabbit femoral bone defect and bone rejuvenation was confirmed by radiological examination, histological examination, fluorochrome labeling study, and micro-CT. μ-CT examination of the regained bone samples exhibited that invasion of mature bone in the pores of the MgP2Sr-dPRF sample was higher than the MgP2Sr which indicated better bone maturation capability of this composition. Quantifiable assessment using oxytetracycline labeling showed 73.55 ± 1.12% new osseous tissue regeneration for MgP2Sr-dPRF samples in contrast to 65.47 ± 1.16% for pure MgP2Sr samples, after 3 months of implantation. Histological analysis depicted the presence of abundant osteoblastic and osteoclastic cells in dPRF-loaded Sr-doped MgP samples as compared to other samples. Radiological studies also mimicked similar results in the MgP2Sr-dPRF group with intact periosteal lining and significant bridging callus formation. The present results indicated that dPRF-loaded Sr-doped magnesium phosphate bioceramics have good biocompatibility, bone-forming ability, and suitable biodegradability in bone regeneration.

GARP Regulates the Immune Capacity of a Human Autologous Platelet Concentrate

Autologous platelet concentrates, like liquid platelet rich fibrin (iPRF), optimize wound healing; however, the underlying immunological mechanisms are poorly understood. Platelets, the main cellular component of iPRF, highly express the protein, Glycoprotein A repetitions predominant (GARP), on their surfaces. GARP plays a crucial role in maintaining peripheral tolerance, but its influence on the immune capacity of iPRF remains unclear. This study analyzed the interaction of iPRF with immune cells implicated in the wound healing process (human monocyte derived macrophages and CD4⁺ T cells) and evaluated the distinct influence of GARP on these mechanisms in vitro. GARP was determined to be expressed on the surface of platelets and to exist as a soluble factor in iPRF. Platelets derived from iPRF and iPRF itself induced a regulatory phenotype in CD4⁺ T cells, shown by increased expression of Foxp3 and GARP as well as decreased production of IL-2 and IFN-γ. Application of an anti-GARP antibody reversed these effects. Additionally, iPRF polarized macrophages to a "M0/M2-like" phenotype in a GARP independent manner. Altogether, this study demonstrated for the first time that the immune capacity of iPRF is mediated in part by GARP and its ability to induce regulatory CD4⁺ T cells.

Initial Healing Effects of Platelet-Rich Plasma (PRP) Gel and Platelet-Rich Fibrin (PRF) in the Deep Corneal Wound in Rabbits

Platelet concentrates (PCs), including platelet-rich plasma (PRP) gel and platelet-rich fibrin (PRF), are autologous blood-derived biomaterials containing numerous growth factors. This study aimed to evaluate the initial healing effects of PRP gel and PRF on deep corneal wounds. Thirty-three eyes from New Zealand white rabbits were divided into four groups: group 1, lamellar keratectomy (LK); group 2, LK + commercial porcine small intestinal submucosal membrane (SIS); group 3, LK + SIS + PRP gel; and group 4, LK + SIS + PRF. Postoperative clinical and histological findings were observed for eight weeks. Group 1 showed no neovascularization during the observation period, and incompletely recovered with a thin cornea. Group 2 showed active healing through neovascularization, and a thick cornea was regenerated through the sufficient generation of myofibroblasts. Although group 3 showed a healing effect similar to that of group 2, angiogenesis and subsequent vessel regression were promoted, and corneal opacity improved more rapidly. In group 4, angiogenesis was promoted during initial healing; however, the incidence of complications, such as inflammation, was high, and myofibroblasts were hardly generated in the corneal stroma, which adversely affected remodeling. In conclusion, while PRP gel is a safe surgical material for promoting remodeling through vascular healing and myofibroblast production in deep corneal wounds, the use of PRF is not recommended.

Histomorphometric Analysis of Differential Regional Bone Regeneration Induced by Distinct Doped Membranes

Our objective is to evaluate the regional regenerative potential of calvarial bone in critical-sized defects in a rabbit model using novel nanostructured silica-loaded membranes doped with zinc or doxycycline. Nanostructured membranes of (MMA)₁-co-(HEMA)₁/(MA)₃-co-(HEA)₂ loaded with 5 wt% of SiO₂ nanoparticles (HOOC-Si-Membranes) were doped with zinc (Zn-HOOC-Si-Membrane) or doxycycline (Dox-HOOC-Si-Membrane). Critical bone defects were created on six New-Zealand-breed rabbit skulls and covered with the membranes. A sham defect without a membrane was used as the control. After six weeks, a histological analysis (toluidine blue technique) was employed to determine the area percentages of newly formed bone, osteoid bone, and soft tissue. The measurements were performed by dividing the total defect area into top (close to the membrane) and bottom (close to the dura mater) regions, or peripheral (adjacent to the old bone) and central (the sum of the remaining zones) regions. The peripheral regions of the defects showed higher osteogenic capacity than the central areas when the membranes were present. The proportion of new bone adjacent to the dura was similar to that adjacent to the membrane only when the HOOC-Si-Membranes and Zn-HOOC-Si-Membranes were used, indicating a direct osteoinductive effect of the membranes.

Does zinc oxide nanoparticles potentiate the regenerative effect of platelet-rich fibrin in healing of critical bone defect in rabbits?

Background

Many encouraging studies confirmed the ability of Zinc Oxide Nanoparticles (ZnONPs) in accelerating bone growth and mineralization. The use of Platelet Rich-Fibrin (PRF) as a sole filling material for large segmental bone defects remains questionable. The objectives are to investigate the regenerative efficacy of autologous Platelet Rich-Fibrin (PRF) and Zinc Oxide Nanoparticles (ZnONPs) in repairing large segmental bone ulnar defects in a randomized controlled study in rabbits using computed tomographic interpretations. A 12 mm critical size defect was surgically induced in the ulna of 30 rabbits (n = 10/ group). In the control group, the defect was left empty. In the PRF group, the defect is filled with PRF. In the PRF/ZnONPs group, the defect is filled with PRF that was inoculated with 0.1 ml of 0.2% ZnONPs. Radiologic healing capacity was evaluated at the first, second, and third postoperative months.

Results

Statistical analysis showed significant differences in the radiologic healing scores between the groups (P = 0.000–0.0001) at all-time points (P = 0.000–0.047) during the study.

Conclusion

Rabbits in the PRF/ZnONPs group showed the highest appreciable bone quality and quantity followed by the PRF group with high quantity but low bone quality meanwhile, rabbits in the control group showed minimal quantity but medium bone quality. Interestingly, the addition of ZnONPs to PRF can accelerate the healing of ulnar critical-size defects in rabbits.

Micro-CT and Histomorphometric Study of Bone Regeneration Effect with Autogenous Tooth Biomaterial Enriched with Platelet-Rich Fibrin in an Animal Model

The aim of this study was to evaluate the potential of tooth biomaterials as bone graft biomaterials for bone healing in rabbits. We prepared tooth biomaterial and platelet-rich fibrin (PRF) to fill the round-shaped defect in the skull of New Zealand white rabbits. These cranial defects were treated with different conditions as follows: group 1, a mixture of tooth biomaterials and platelet-rich fibrin (PRF); group 2, only tooth biomaterials; group 3, only PRF; and group 4, the unfilled control group. Specimens of the filled sites were harvested for analysis with microscopic computerized tomography (micro-CT) and histomorphology at 4 and 8 weeks. As a result of micro-CT, at 4 weeks, the bone volume percentages in groups 1 and 2 were 50.33 ± 6.35 and 57.74 ± 3.13, respectively, and that in the unfilled control group was 42.20 ± 10.53 (p = 0.001). At 8 weeks, the bone volume percentages in groups 1 and 2 were 53.73 ± 9.60 and 54.56 ± 8.44, respectively, and that in the unfilled control group was 37.86 ± 7.66 (p = 0.002). The difference between the experimental group 3 and the unfilled control group was not statistically significant. Histomorphologically, the total new bone was statistically different.

A review of biomimetic scaffolds for bone regeneration: Toward a cell-free strategy

In clinical terms, bone grafting currently involves the application of autogenous, allogeneic, or xenogeneic bone grafts, as well as natural or artificially synthesized materials, such as polymers, bioceramics, and other composites. Many of these are associated with limitations. The ideal scaffold for bone tissue engineering should provide mechanical support while promoting osteogenesis, osteoconduction, and even osteoinduction. There are various structural complications and engineering difficulties to be considered. Here, we describe the biomimetic possibilities of the modification of natural or synthetic materials through physical and chemical design to facilitate bone tissue repair. This review summarizes recent progresses in the strategies for constructing biomimetic scaffolds, including ion-functionalized scaffolds, decellularized extracellular matrix scaffolds, and micro- and nano-scale biomimetic scaffold structures, as well as reactive scaffolds induced by physical factors, and other acellular scaffolds. The fabrication techniques for these scaffolds, along with current strategies in clinical bone repair, are described. The developments in each category are discussed in terms of the connection between the scaffold materials and tissue repair, as well as the interactions with endogenous cells. As the advances in bone tissue engineering move toward application in the clinical setting, the demonstration of the therapeutic efficacy of these novel scaffold designs is critical.

Does Platelet-Rich Fibrin Enhance the Early Angiogenetic Potential of Different Bone Substitute Materials? An In Vitro and In Vivo Analysis

The impaired angiogenic potential of bone substitute materials (BSMs) may limit regenerative processes. Therefore, changes in the angiogenetic properties of different BSMs in combination with platelet-rich fibrin (PRF) in comparison to PRF alone, as well as to native BSMs, were analyzed in vitro and in vivo to evaluate possible clinical application. In vitro, four BSMs of different origins (allogeneic, alloplastic, and xenogeneic) were biofunctionalized with PRF and compared to PRF in terms of platelet interaction and growth factor release (vascular endothelial growth factor (VEGF), tissue growth factor ß (TGFß) and platelet-derived growth factor (PDGF)) after 15 min. To visualize initial cell–cell interactions, SEM was performed. In vivo, all BSMs (±PRF) were analyzed after 24 h for new-formed vessels using a chorioallantoic membrane (CAM) assay. Especially for alloplastic BSMs, the addition of PRF led to a significant consumption of platelets (p = 0.05). PDGF expression significantly decreased in comparison to PRF alone (all BSMs: p < 0.013). SEM showed the close spatial relation of each BSM and PRF. In vivo, PRF had a significant positive pro-angiogenic influence in combination with alloplastic (p = 0.007) and xenogeneic materials (p = 0.015) in comparison to the native BSMs. For bio-activated xenogeneic BSMs, the branching points were also significantly increased (p = 0.005). Finally, vessel formation was increased for BSMs and PRF in comparison to the native control (allogeneic: p = 0.046; alloplastic: p = 0.046; and xenogeneic: p = 0.050). An early enhancement of angiogenetic properties was demonstrated when combining BSMs with PRF in vitro and led to upregulated vessel formation in vivo. Thus, the use of BSMs in combination with PRF may trigger bony regeneration in clinical approaches.

Doxycycline and Zinc Loaded Silica-Nanofibrous Polymers as Biomaterials for Bone Regeneration

The main target of bone tissue engineering is to design biomaterials that support bone regeneration and vascularization. Nanostructured membranes of (MMA)₁-co-(HEMA)₁/(MA)₃-co-(HEA)₂ loaded with 5% wt of SiO₂-nanoparticles (HOOC-Si-Membrane) were doped with zinc (Zn-HOOC-Si-Membrane) or doxycycline (Dox-HOOC-Si-Membrane). Critical bone defects were effectuated on six New Zealand-bred rabbit skulls and covered with the membranes. After six weeks, the bone architecture was evaluated with micro computed tomography. Three histological analyses were utilized to analyse bone regeneration, including von Kossa silver nitrate, toluidine blue and fluorescence. All membrane-treated defects exhibited higher number of osteocytes and bone perimeter than the control group without the membrane. Zn-HOOC-Si-Membranes induced higher new bone and osteoid area than those treated with HOOC-Si-Membranes, and control group, respectively. Zn-HOOC-Si-Membranes and Dox-HOOC-Si-Membranes attained the lowest ratio M1 macrophages/M2 macrophages. Dox-HOOC-Si-Membranes caused the lowest number of osteoclasts, and bone density. At the trabecular new bone, Zn-HOOC-Si-Membranes produced the highest angiogenesis, bone thickness, connectivity, junctions and branches. Zn-HOOC-Si-Membranes enhanced biological activity, attained a balanced remodeling, and achieved the greatest regenerative efficiency after osteogenesis and angiogenesis assessments. The bone-integrated Zn-HOOC-Si-Membranes can be considered as bioactive modulators provoking a M2 macrophages (pro-healing cells) increase, being a potential biomaterial for promoting bone repair.

A 3D journey on virtual surfaces and inner structure of ossa genitalia in Primates by means of a non-invasive imaging tool

Novel bio-imaging techniques such as micro-Computed Tomography provide an opportunity to investigate animal anatomy and morphology by overcoming limitations imposed by traditional anatomical drawings. The primate genital bones are complex anatomical structures whose occurrence in both male penis (baculum) and female clitoris (baubellum) may be difficult to assess in individual cadavers. We tested a 3-step methodological protocol, including different techniques ranging from inexpensive/simple to more expensive/sophisticated ones, by applying it to a sample of primate species, and resulting in different levels of data complexity: (1) presence/absence manual palpation method; (2) 2D X-ray plates; 3) 3D micro-CT scans. Manual palpation failed on 2 out of 23 specimens by detecting 1 false negative and 1 false positive; radiography failed once confirming the false positive, however firmly disproved by micro-CT; micro-CT analysis reported the presence of 9 bacula out of 11 male specimens and 1 baubellum out of 12 female specimens. A different baculum position was identified between strepsirrhine and haplorrhine species. We also aim to assess micro-CT as a non-invasive technique providing updated anatomical descriptions of primate ossa genitalia. Micro-CT 3D volumes showed the surface of some bones as rough, with a jagged appearance, whereas in others the surface appeared very smooth and coherent. In addition, four main types of bone internal structure were identified: 1) totally hollow; 2) hollow epiphyses and solid diaphysis with few or several channels inside; 3) totally solid with intricate Haversian channels; 4) totally solid with some channels (structure of single baubellum scanned). Ossa genitalia appeared as a living tissue having its own Haversian-like channels. The high resolution of micro-CT 3D-images of primate genital bones disclosed additional form variability to that available from genital bone 2D images of previous studies, and showed for the first time new internal and external morphological characters. Moreover, micro-CT non-invasive approach proved appropriate to recover much of scientific knowledge still hidden and often neglected in both museum specimens and primate cadavers only destined to necropsy.

Platelet-rich fibrin suppresses in vitro osteoclastogenesis

Background

Platelet‐rich fibrin (PRF) membranes can preserve alveolar ridge dimension after tooth extraction. Thus, it can be presumed that PRF suppresses the catabolic events that are caused by osteoclastic bone resorption.

Methods

To address this possibility, we investigated the impact of soluble extracts of PRF membranes on in vitro osteoclastogenesis in murine bone marrow cultures. Osteoclastogenesis was induced by exposing murine bone marrow cultures to receptor activator of nuclear factor kappa B ligand (RANKL), macrophage colony‐stimulating factor (M‐CSF) and transforming growth factor‐beta 1 (TGF‐β1) in the presence or absence of PRF. Osteoclastogenesis was evaluated based on histochemical, gene expression, and resorption analysis. Viability was confirmed by formation of formazan crystals, live‐dead staining and caspase‐3 activity assay.

Results

We report here that in vitro osteoclastogenesis is greatly suppressed by soluble extracts of PRF membranes as indicated by tartrate‐resistant acid phosphatase (TRAP) staining and pit formation. In support of the histochemical observations, soluble extracts of PRF membranes decreased expression levels of the osteoclast marker genes TRAP, Cathepsin K, dendritic cell‐specific transmembrane protein (DCSTAMP), nuclear factor of activated T‐cells (NFATc1), and osteoclast‐associated receptor (OSCAR). PRF membranes, however, cannot reverse the process once osteoclastogenesis has evolved.

Conclusion

These in vitro findings indicate that PRF membranes can inhibit the formation of osteoclasts from hematopoietic progenitors in bone marrow cultures. Overall, our results imply that the favorable effects of PRF membranes in alveolar ridge preservation may be attributed, at least in part, by the inhibition of osteoclastogenesis.

Effects of leukocyte- and platelet-rich fibrin associated or not with bovine bone graft on the healing of bone defects in rats with osteoporosis induced by ovariectomy

OBJECTIVE

To evaluate the healing of critical size defects (CSDs) in calvaria of rats with osteoporosis induced by ovariectomy and treated with leukocyte- and platelet-rich fibrin (L-PRF) associated or not with bovine bone graft (XENO).

MATERIAL AND METHODS

A total of 32 rats underwent a bilateral ovariectomy procedure. After 3 months, one 5 mm in diameter CSD was created in the middle of the calvaria of each animal. In group C, defect was filled with blood clot only. In PRF, XENO, and PRF-XENO groups, defects were filled with 0.1 ml of L-PRF, 0.1 ml of XENO, and a mixture of 0.1 ml of L-PRF plus 0.1 ml of XENO, respectively. L-PRF compressed clots were used to cover the defects in PRF and PRF-XENO groups. Animals were submitted to euthanasia at 30 postoperative days. Histomorphometric, microtomographic, and immunohistochemical analyses were performed.

RESULTS

PRF-XENO group presented greater amount of neoformed bone (NB) when compared with XENO group, as well as higher expression of vascular endothelial growth factor (VEGF), osteocalcin (OCN), and bone morphogenetic protein (BMP-2/4) (p < .05). PRF group presented increased amount of NB and higher expression of VEGF, OCN, BMP-2/4, and Runt-related transcription factor 2 (RUNX-2) when compared with group C (p < .05).

CONCLUSIONS

(a) The isolated use of L-PRF clot can improve bone neoformation in CSDs in rats with osteoporosis induced by ovariectomy, but seems to lead to decreased amount of bone neoformation when compared to the isolated use of XENO; (b) L-PRF potentiates the healing of XENO in rats with osteoporosis induced by ovariectomy.