The effects of newly formed synthetic peptide on bone regeneration in rat calvarial defects

Animal models for testing biomaterials in periodontal regeneration

Periodontitis is a prevalent oral disease. It can cause tooth loss and has a significant impact on patients' quality of life. While existing treatments can only slow the progression of periodontitis, they are unable to achieve complete regeneration and functional reconstruction of periodontal tissues. As a result, regenerative therapies based on biomaterials have become a focal point of research in the field of periodontology. Despite numerous studies reporting the superiority of new materials in periodontal regeneration, limited progress has been made in translating these findings into clinical practice. This may be due to the lack of appropriate animal models to simulate the tissue defects caused by human periodontitis. This review aims to provide an overview of established animal models for periodontal regeneration, examine their advantages and limitations, and outline the steps for model construction. The objective is to determine the most relevant animal models for periodontal regeneration based on the hypothesis and expected outcomes.

Development of a thermosensitive statin loaded chitosan-based hydrogel promoting bone healing

Statins have been proposed as potential adjuvant to periodontal treatment due to their pleiotropic properties. A new thermosensitive chitosan hydrogel loaded with statins (atorvastatin and lovastatin) nanoemulsions was synthesized to allow a spatially controlled local administration of active compounds at lesion site. Spontaneous nano-emulsification method was used to synthesize statins loaded nanoemulsions. In vitro, atorvastatin and lovastatin loaded nanoemulsions were cytocompatible and were able to be uptake by oral epithelial cells. Treatment of Porphyromonas gingivalis infected oral epithelial cells and gingival fibroblasts with atorvastatin and lovastatin loaded nanoemulsions decreased significantly pro-inflammatory markers expression (TNF-α and IL-1β) and pro-osteoclastic RANKL. Nevertheless, such treatment induced the expression of Bone sialoprotein 2 (BSP2) in osteoblast emphasizing the pro-healing properties of atorvastatin and lovastatin nanoemulsions. In vivo, in a calvarial bone defect model (2 mm), treatment with the hydrogel loaded with atorvastatin and lovastatin nanoemulsions induced a significant increase of the neobone formation in comparison with systemic administration of statins. This study demonstrates the potential of this statins loaded hydrogel to improve bone regeneration and to decrease soft tissue inflammation. Its use in the specific context of periodontitis management could be considered in the future with a reduced risk of side effects.

The Effect of Strontium Ranelate Gel on Bone Formation in Calvarial Critical Size Defects

AIM:

The current study was designed to investigate the effectiveness of locally applied Strontium ranelate to induce bone formation.

MATERIALS AND METHODS:

Forty-eight female rats were divided into six groups (eight rats in each group): The three test groups included Strontium (SR) 2.5 mg, 5 mg and 10 mg that was dissolved in methylcellulose gel. The control groups included methylcellulose, simvastatin 5 mg and a negative control where the defect was left to heal without any intervention. At 44 days the groups were sacrificed, and the bone defects were assessed histomorphometically to assess bone formation. The data was statistically analysed.

RESULTS:

There was a statistically significant difference in the amount of new bone formation between all groups, where the 2.5 mg SR group showed the highest median bone percentage, is 41.95 %, followed by the 5, and 10 mg SR demonstrating a median bone are a percentage of 39.89%, and 30.19% respectively. Simvastatin showed a median bone percentage of 36.07 %, while the methylcellulose and the negative control groups demonstrated the lowest median area percentage of 23.12 and 20.70 % respectively.

CONCLUSIONS:

The study showed that the local application of an SR could up-regulate the bone formation and may prove to be a cost-effective method of bone regeneration.

The Effects of Nigella Sativa Seed Extract on Bone Healing in an Experimental Model

The purpose of this study was to histologically evaluate the effects on bone healing of nigella sativa seed extract applied on calvarial defects in an ovariectomized rat model. The study included 32 female rats weighing 280 to 310 g with an average age of 3 months. A defect was created with a trephine burr on each rat calvarium. The rats were divided into 2 groups (control and study) of 8 animals each. All the defects were grafted with a gelatin sponge mixed with normal saline. In the study group, nigella sativa seed extract was applied systemically using an oro-gastric tube. Half of the animals in each group were sacrificed after 2 weeks, and the others after 4 weeks. In the control groups, the defects were not completely filled with regenerated bone. Osteoblast cells were observed more in the study groups. A higher rate of osteoclasts was determined in the control groups. In addition, the nigella sativa group had a statistically greater amount of bone formation than the others group at both 2 weeks and 4 weeks (P <0.05). The systemic application of nigella sativa seed extract demonstrated incredibly positive effects on enhanced bone healing in this experimental osteoporotic model.

Effect of Resorbable Collagen Plug on Bone Regeneration in Rat Critical-Size Defect Model

OBJECTIVE

The purpose of this investigation was to examine the effect of resorbable collagen plug (RCP) on bone regeneration in rat calvarial critical-size defects.

METHODS

About 5-mm-diameter calvarial defects were created in forty 12-week-old male Sprague-Dawley rats and implanted with or without RCP. Animals were killed at 1, 2, 4, and 8 weeks postoperatively. After being killed, specimens were collected and subjected to micro-computed tomography (μCT) and histological analysis.

RESULTS

The μCT showed a significant increase of newly formed bone volume/tissue volume in RCP-implanted defect compared with controls at all designated time points. After 8 weeks, the defects implanted with RCP displayed almost complete closure. Hematoxylin and eosin staining of the decalcified sections confirmed these observations and evidenced active bone regeneration in the RCP group. In addition, Masson's trichrome staining demonstrated that RCP implantation accelerated the process of collagen maturation.

CONCLUSIONS

The RCP enhances bone regeneration in rat critical-size cranial defects, which suggest it might be a desired material for bone defect repair.

Effects of Ankaferd BloodStopper on bone healing in an ovariectomized osteoporotic rat model

Bone defects resulting from oncological surgical resections, congenital facial anomalies, trauma or infection represent a significant and common clinical problem. The present study aimed to evaluate the effects of a commercially-available medicinal plant extract product, Ankaferd BloodStopper (ABS), on bone healing. The present study was performed on 24 female ovariectomized (OVX) rats. A defect on each rat calvarium was created using a trephine burr prior to the rats being divided into two groups. Defects were grafted with a gelatin sponge soaked with normal saline (control group) or plant extract (experimental group). Half of the animals were sacrificed after 2 weeks and the others after 4 weeks. In the control group, the defects were not filled with regenerated bone. By contrast, in the experimental group, all defect areas had an increased amount of regenerated bone and connective tissue. Osteoblastic activity appeared to be greater in the experimental group however, osteoclastic activity was observed to be higher in the control group. At 2 and 4 weeks, there was a significant difference in the amount of newly regenerated bone observed in the experimental group compared with the control group (P<0.05). Therefore, the results of the present study indicated that local ABS application had a positive effect on bone healing in the OVX rat model.

The Effect of Local Rosuvastatin on Mandibular Fracture Healing

Mandibular fracture is the most common injury seen in facial fractures and plays an important role for oral and maxillofacial surgery department. The purpose of this study is to investigate the potential of the local administration of rosuvastatin (RSV) on mandibular fracture healing in rats. Thirty-two rats were divided into 4 groups: group C-14 (control), group R-14, group C-28 (control), and group R-28. A unilateral standard vertical osteotomy was performed right side of the mandibula extending from the tooth to the mandibular basis for each animal. In groups C-14 and C-28 sterile saline treated absorbable collogen sponge was applied to the fracture area, in groups R-14 and R-28 absorbable collogen sponge with saline solution containing 1 mg RSV was applied to the fracture area. Animals in groups C-14 and R-14 were euthanized on the 14th day, groups C-28 and R-28 were euthanized on the 28th day after operation. Stereologic analyses were performed. New bone area and connective tissue volumes were measured. Stereologic analysis showed that group R-14 had significantly more new bone at 2 weeks compared with group C-14. Connective tissue volumes were also significantly higher in R-14. New bone and connective tissue volume differences were not statistically significant between groups C-28 and R-28. Locally administered RSV enhances early bone regeneration on mandibular fracture in rats.

The Local Effect of Puerarin on Critical-Sized Calvarial Defects

Pueraria, the root of Pueraria lobata, is a commonly used herb in alternative medicine. This study evaluates the effect of puerarin and autogenous graft material combination on bone regeneration in calvarial critical-sized bone defects. Twenty-four rats were randomly divided into 3 groups of 8 rats each. A 5-mm diameter critical-sized defect was created in the calvarium of each animal. In group C, defects were left unfilled and were allowed to heal spontaneously without the use of any grafting material. Critical-sized bone defect created in animals receiving no treatment. In group ABG, defects were filled with autologous bone graft only. In group P-ABG, defects were filled with autologous bone graft and puerarin combination. All animals were euthanized at 28 days postoperative. Stereologic analyses were performed. New bone area and connective tissue volumes were measured. Stereologic analysis showed that the difference between grafted groups (P-ABG and ABG) and group C was statistically significant with a mean bone formation of 1.13 ± 0.09, 1.11 ± 0.11, and 0.31 ± 0.09 mm respectively (P ≤0.05). The connective tissue volumes were also statistically higher in groups P-ABG and ABG (P ≤0.05). Puerarin has positive effect on new bone formation in autogenous grafted critical-sized bone defects.

Taking cues from the extracellular matrix to design bone-mimetic regenerative scaffolds

There is an ongoing need for effective materials that can replace autologous bone grafts in the clinical treatment of bone injuries and deficiencies. In recent years, research efforts have shifted away from a focus on inert biomaterials to favor scaffolds that mimic the biochemistry and structure of the native bone extracellular matrix (ECM). The expectation is that such scaffolds will integrate with host tissue and actively promote osseous healing. To further enhance the osteoinductivity of bone graft substitutes, ECM-mimetic scaffolds are being engineered with a range of growth factors (GFs). The technologies used to generate GF-modified scaffolds are often inspired by natural processes that regulate the association between endogenous ECMs and GFs. The purpose of this review is to summarize research centered on the development of regenerative scaffolds that replicate the fundamental collagen-hydroxyapatite structure of native bone ECM, and the functionalization of these scaffolds with GFs that stimulate critical events in osteogenesis.

Effects of caffeic acid phenethyl ester on wound healing in calvarial defects

OBJECTIVE

The aim of this study is to analyze histologically the effect of CAPE on bone healing of Critical Size Defect (CSD) in rat calvaria.

STUDY DESIGN

Thirty-two 3-month-old male rats were used. The animals were randomly divided into four groups. Group A received isotonic saline solution, Group B received CAPE (50 mmol/kg) locally, Group C received CAPE (100 mmol/kg) locally and Group D received CAPE (10 mmol/kg/day i.p. for 28 days) systematically. A 5-mm diameter calvarial defect was created in the right side of the parietal bone without damaging the underlying dura mater. Twenty-eight days after the surgery, all the animals were sacrificed. The original defect area was removed from the animal's calvarium bone en bloc. Beginning at the center of the surgical defect, serial sections of 6 µm thick were cut longitudinally. The sections were stained with hematoxylin and eosin for analysis under a light microscope. The sections were analyzed for the presence of inflammatory infiltrate, connective tissue formation and new bone formation. Computer-assisted histomorphometic measurements were carried out with an automated image analysis system.

RESULTS

The total new bone areas were significantly greater in group D than in all groups and group C was statistically insignificant from the other groups (p < 0.05). Group B had a greater, but not statistically significant (p > 0.05), amount of total regenerated bone area than the control group.

CONCLUSION

The results indicate that 100 mmol/kg topical and 10 mmol/kg/day systemic application of CAPE increases bone healing, especially with systemic application.

The effect of local simvastatin application on critical size defects in the diabetic rats

OBJECTIVES

To evaluate bone-healing effects of local simvastatin application to critical size defects (CSDs) in the experimental diabetes mellitus (DM) rat model.

MATERIALS AND METHODS

A total of 35 male Sprague-Dawley rats with an average weight of 350 g and aged 3 months were used in this study. The rats were divided into five groups of seven animals each: passive control (group A), active control (group B), 0.5 mg simvastatin (group C), 1.0 mg simvastatin (group D), and 1.5 mg simvastatin (group E). Streptozotocin was used to induce Type 1 diabetes in all rats. Eight mm CSDs were created under anesthesia in each rat calvarium. CSDs were left empty in group A. Defects in group B were grafted alone with a gelatin sponge mixed with normal saline. Defects in the experimental groups (groups A, B, and C) were grafted with gelatin sponge mixed saline solutions contain 0.5, 1.0, 1.5 mg simvastatin. Rats were sacrificed after 1 month, and the defects were prepared for radiologic and histomorphometric assessment of regenerated bone.

RESULTS

None of the specimens exhibited complete closure of new bone across the 8-mm defect. A correlation between computed tomography and histomorphometric analysis was not determined. Both amount of volume and area of regenerated bone were found higher in the experimental groups than in the control groups. However, these values were not found statistically significant degree (P < 0.05) for each groups. The density of regenerated bone in the region of interest was higher in the control groups in contrast to in the experimental groups. However, statistical significance was just found between groups C and A and between groups C and B (P < 0.05).

CONCLUSION

The local simvastatin application enhanced healing of the bone defects in the diabetic rat model CSDs.

Polyglutamate directed coupling of bioactive peptides for the delivery of osteoinductive signals on allograft bone

Allograft bone is commonly used as an alternative to autograft, however allograft lacks many osteoinductive factors present in autologous bone due to processing. In this study, we investigated a method to reconstitute allograft with osteoregenerative factors. Specifically, an osteoinductive peptide from collagen I, DGEA, was engineered to express a heptaglutamate (E7) domain, which binds the hydroxyapatite within bone mineral. Addition of E7 to DGEA resulted in 9× greater peptide loading on allograft, and significantly greater retention after a 5-day interval with extensive washing. When factoring together greater initial loading and retention, the E7 domain directed a 45-fold enhancement of peptide density on the allograft surface. Peptide-coated allograft was also implanted subcutaneously into rats and it was found that E7DGEA was retained in vivo for at least 3 months. Interestingly, E7DGEA peptides injected intravenously accumulated within bone tissue, implicating a potential role for E7 domains in drug delivery to bone. Finally, we determined that, as with DGEA, the E7 modification enhanced coupling of a bioactive BMP2-derived peptide on allograft. These results suggest that E7 domains are useful for coupling many types of bone-regenerative molecules to the surface of allograft to reintroduce osteoinductive signals and potentially advance allograft treatments.

Cobalt chromium alloy with immobilized BMP peptide for enhanced bone growth

Cobalt chromium (CoCr) alloys are widely used in orthopedic practice, however, lack of integration into the bone for long-term survival often occurs, leading to implant failure. Revision surgery to address such a failure involves increased risks, complications, and costs. Advances to enhancement of bone-implant interactions would improve implant longevity and long-term results. Therefore, we investigated the effects of BMP peptide covalently grafted to CoCr alloy on osteogenesis. The BMP peptide was derived from the knuckle epitope of bone morphogenic protein-2 (BMP-2) and was conjugated via a cysteine amino acid at the N-terminus. X-ray photoelectron spectroscopy and o-phthaldialdehyde were used to verify successful grafting at various stages of surface functionalization. Surface topography was evaluated from the surface profile determined by atomic force microscopy. Osteoblastic cells (MC3T3-E1) were seeded on the substrates, and the effects of BMP peptide on osteogenic differentiation were evaluated by measuring alkaline phosphatase (ALP) activity and calcium mineral deposition. The functionalized surfaces showed a twofold increase in ALP activity after 2 weeks incubation and a fourfold increase in calcium content after 3 weeks incubation compared to the pristine substrate. These findings are potentially useful in the development of improved CoCr implants for use in orthopedic applications.

Orthopaedic Implant Technology: Biomaterials from Past to Future

Orthopaedic implant technology is heavily based on the development and use of biomaterials. These are non-living materials (e.g. metals, polymers and ceramics) that are introduced into the human body as constituents of implants that fulfil or replace some important function. Examples would be prosthetic joint replacements and fracture fixation implants. For orthopaedic biomaterials to succeed in their desired functions and outcomes in the body, a number of factors need to be considered. The most obvious mechanical properties of the implants are that they need to suit their intended function, and various classes and types of biomaterials have been developed and characterised for use in different implant components depending on their demands. Less well understood but no less important are the interactions that occur between the constituent biomaterials and the living cells and tissues, both of the human host as well as pathogens such as bacteria. Biomaterials used for orthopaedic applications are generally considered to be biocompatible. However, adverse effects arising from interactions at the implant interface can result in various modes of implant failure, such as aseptic loosening and implant infection. This review paper uses the illustrative example of total hip replacement (which has been called the operation of the century) to highlight key points in the evolution of orthopaedic biomaterials. It will also examine research strategies that seek to address some of the major problems that orthopaedic implant surgery are facing today. Keywords: Biocompatibility, Biomaterials, Joint Replacement, Orthopaedic Implants