Translational value of sheep as animal model to study sinus augmentation

Sheep's Head as an Anatomic Model for Basic Training in Endoscopic Sinus Surgery

Background and Objectives: This study aims to establish the sheep head as a viable anatomical model for training in functional endoscopic sinus surgery through comprehensive anatomical examination and training-based assessment of participants' satisfaction. Materials and Methods: Participants were divided into three groups according to their prior experience in endoscopic sinus surgery; in total, 24 participants were included. Each participant in the study was assigned to perform the designated procedures on a single sheep's head. Following the completion of the procedures, each participant was provided with a 14-item comprehensive satisfaction questionnaire with a scale attributed from 1 to 5. The normality of distribution was checked by applying the Shapiro-Wilk Test. The Kruskal-Wallis test was applied to compare study group sentiment of agreement towards individual procedures. Results: No significant differences were noted between the answers of the different groups. For the resident group, the average satisfaction score was 4.09 ± 0.54; junior specialist group 4.00 ± 0.55; for the senior specialist group overall satisfaction average score was 4.2 ± 0.77. Conclusions: The sheep's head can be successfully used for learning and practicing manual skills and the use of instruments specific to functional endoscopic sinus surgery. Moreover, the sheep head model can be used for training in other diagnostic or surgical procedures in the field of otorhinolaryngology, such as endoscopy of the salivary glands, open laryngotracheal surgery, or in otologic surgery, but also in other different surgical fields such as neurosurgery, ophthalmology or plastic surgery. Despite the differences between the ovine model and human anatomy, it provides a resourceful and cost-effective model for beginners in endoscopic nasal surgery.

The Effectiveness of Internal Maxillary Sinus Elevation Using Controlled Hydrodynamic or Pneumatic Pressure: An Ex-vivo Experimental and Preliminary Animal Study

Objective

The aim of this experimental study was to test the possibility of applying internal sinus elevation techniques using controlled hydrodynamic or pneumatic pressure and evaluate their elevation effectiveness.

Materials and methods

A device was specially designed for this study and was used to elevate the sinus membrane internally in 12 halves of freshly slaughtered sheep heads. The sample was divided into two groups randomly according to the type of controlled pressure applied (hydrodynamic or pneumatic). The elevation height of the membrane was measured in addition to investigating the presence or absence of perforation.

Results

The maxillary sinus membranes started to be elevated at an average pressure value of 21.6 ± 7.5 millibars (mbar) when hydrodynamic pressure was applied, and at an average pressure value of 23.3 ± 8.1 mbar when pneumatic pressure was applied. The mean values ​​of elevation height after applying the controlled hydrodynamic and pneumatic pressure were 13.00 ± 2.76 and 10.33 ± 3.88 mm, respectively. No perforations occurred in either of the groups.

Conclusions

The use of a controlled hydrodynamic or pneumatic pressure, which is appropriate for the characteristics of the maxillary sinus membrane in the process of internal elevation, is effective, and it yielded an amount of lifting similar to that we get when using the external elevation.

Timing of orthodontic tooth movement in bone defects repaired with synthetic scaffolds: A scoping review of animal studies

OBJECTIVE

The optimal timing of orthodontic tooth movement (OTM) could allow earlier tooth movements across alveolar bone defects while minimizing the adverse effects. The objective of this scoping systematic review was therefore designed to review pre-clinical animal studies on the ideal protocol for the timing of orthodontic traction across alveolar defects augmented with synthetic scaffolds.

DESIGN

Following the PRISMA-ScR guidelines, three electronic databases were searched (Pubmed, Scopus and Web of Science).

RESULTS

A total of twelve studies were included in the final review that reported on small-animal (rats, guinea pigs, rabbits) and large-animal (dogs and goats) models. Based on the grafting biomaterials, eight papers used cell-free scaffolds, four articles utilised cell-based scaffolds. The timing protocol for the initiation of OTM employed in the studies ranged from immediate to 6 months after surgical grafting. Only four studies included autologous bone graft (gold standard) as positive control. Most papers reported positive results with regards to the rate of OTM and bone augmentation effects while only a few reported side effects such as root resorptions. Overall, the included articles showed a massive heterogeneity in terms of the animal bone defect model characteristics, scaffold materials, study designs, parameters of OTM and methods of analysis.

CONCLUSION

Since there was inadequate evidence to identify the optimal protocol of OTM, optimization of animal bone defect models and outcome measurements is needed to improve the translational ability of future studies.

Characteristics of Large Animal Models for Current Cell-Based Oral Tissue Regeneration

The recent advances in the field of cell-based therapeutics open promising perspectives for oral tissue regeneration. The development of large animal models, which overcome the limits of the rodent models and allow to emulate clinical situations, is crucial for the validation of regenerative strategies to move toward clinical application. Currently, porcine, canine, and ovine models are mainly developed for oral regeneration and their specific characteristics have an impact on the outcomes of the studies. Thus, this systematic review investigates the application of porcine, canine, and ovine models in present cell-based oral regeneration, according to the species characteristics and the targeted tissue to regenerate. A customized search of PubMed, EMBASE, Scopus, and Web of Science databases from January 2015 to March 2020 was conducted. Relevant articles about cell-based oral tissues engineering in porcine, canine, and ovine models were evaluated. Among the evaluated articles, 58 relevant studies about cell-based oral regeneration in porcine, canine, and ovine models matched the eligibility criteria and were selected for full analysis. Porcine models, the most similar species with humans, were mostly used for bone and periodontium regeneration; tooth regeneration was reported only in pig, except for one study in dog. Canine models were the most transversal models, successfully involved for all oral tissue regeneration and notably in implantology. However, differences with humans and ethical concerns affect the use of these models. Ovine models, alternative to porcine and canine ones, were mainly used for bone and, scarcely, periodontium regeneration. The anatomy and physiology of these animals restrain their involvement. If consistency was found in defect specificities and cell trends among different species animal models of bone, dentin-pulp complex, or tooth regeneration, variability appeared in periodontium. Regeneration assessment methods were more elaborate in porcines and canines than in ovines. Risk of bias was low for selection, attrition and reporting, but unclear for performance and detection. Overall, if none of the large animal models can be considered an ideal one, they are of deemed importance for oral cell-based tissue engineering and researchers should consider their relevance to establish favorable conditions for a given preclinical cell-based therapeutics.

Synthetic Scaffold/Dental Pulp Stem Cell (DPSC) Tissue Engineering Constructs for Bone Defect Treatment: An Animal Studies Literature Review

Background: Recently a greater interest in tissue engineering for the treatment of large bone defect has been reported. The aim of the present systematic review and meta-analysis was to investigate the effectiveness of dental pulp stem cells and synthetic block complexes for bone defect treatment in preclinical in vivo articles. Methods: The electronic database and manual search was conducted on Pubmed, Scopus, and EMBASE. The papers identified were submitted for risk-of-bias assessment and classified according to new bone formation, bone graft characteristics, dental pulp stem cells (DPSCs) culture passages and amount of experimental data. The meta-analysis assessment was conducted to assess new bone formation in test sites with DPSCs/synthetic blocks vs. synthetic block alone. Results: The database search identified a total of 348 papers. After the initial screening, 30 studies were included, according to the different animal models: 19 papers on rats, 3 articles on rabbits, 2 manuscripts on sheep and 4 papers on swine. The meta-analysis evaluation showed a significantly increase in new bone formation in favor of DPSCs/synthetic scaffold complexes, if compared to the control at 4 weeks (Mean Diff: 17.09%, 95% CI: 15.16–18.91%, p < 0.01) and at 8 weeks (Mean Diff: 14.86%, 95% CI: 1.82–27.91%, p < 0.01) in rats calvaria bone defects. Conclusion: The synthetic scaffolds in association of DPSCs used for the treatment of bone defects showed encouraging results of early new bone formation in preclinical animal studies and could represent a useful resource for regenerative bone augmentation procedures

Placental Stem Cells from Domestic Animals: Translational Potential and Clinical Relevance

The field of regenerative medicine is moving toward clinical practice in veterinary science. In this context, placenta-derived stem cells isolated from domestic animals have covered a dual role, acting both as therapies for patients and as a valuable cell source for translational models. The biological properties of placenta-derived cells, comparable among mammals, make them attractive candidates for therapeutic approaches. In particular, stemness features, low immunogenicity, immunomodulatory activity, multilineage plasticity, and their successful capacity for long-term engraftment in different host tissues after autotransplantation, allo-transplantation, or xenotransplantation have been demonstrated. Their beneficial regenerative effects in domestic animals have been proven using preclinical studies as well as clinical trials starting to define the mechanisms involved. This is, in particular, for amniotic-derived cells that have been thoroughly studied to date. The regenerative role arises from a mutual tissue-specific cell differentiation and from the paracrine secretion of bioactive molecules that ultimately drive crucial repair processes in host tissues (e.g., anti-inflammatory, antifibrotic, angiogenic, and neurogenic factors). The knowledge acquired so far on the mechanisms of placenta-derived stem cells in animal models represent the proof of concept of their successful use in some therapeutic treatments such as for musculoskeletal disorders. In the next future, legislation in veterinary regenerative medicine will be a key element in order to certify those placenta-derived cell-based protocols that have already demonstrated their safety and efficacy using rigorous approaches and to improve the degree of standardization of cell-based treatments among veterinary clinicians.

Evaluation of the Osteogenic Potential of Different Scaffolds Embedded with Human Stem Cells Originated from Schneiderian Membrane: An In Vitro Study

BACKGROUND

Novel treatments for bone defects, particularly in patients with poor regenerative capacity, are based on bone tissue engineering strategies which include mesenchymal stem cells (MSCs), bioactive factors, and convenient scaffold supports.

OBJECTIVE

In this study, we aimed at comparing the potential for different scaffolds to induce osteogenic differentiation of human maxillary Schneiderian sinus membrane- (hMSSM-) derived cells. Methods. hMSSM-derived cells were seeded on gelatin, collagen, or Hydroxyapatite β-Tricalcium phosphate-Fibrin (Haβ-TCP-Fibrin) scaffolds. Cell viability was determined using an MTT assay. Alizarin red staining method, Alkaline phosphatase (ALP) activity assay, and quantitative real-time PCR analysis were performed to assess hMSSM-derived cells osteogenic differentiation.

RESULTS

Cell viability, calcium deposition, ALP activity, and osteoblastic markers transcription levels were most striking in gelatin scaffold-embedded hMSSM-derived cells.

CONCLUSION

Our findings suggest a promising potential for gelatin-hMSSM-derived cell construct for treating bone defects.

Applications of Mesenchymal Stem Cells in Sinus Lift Augmentation as a Dental Implant Technology

The potential application of stem cell biology in human dentistry is a new and emerging field of research. The objective of the current review was to study the efficiency of mesenchymal stem cells (MSCs) in sinus lift augmentation (SLA). A literature review was performed in PubMed Central using MeSH keywords such as sinus lift, MSCs, dental implants, and augmentation. The searches involved full-text papers written in English, published in the past 10 years (2007–2017). The review included in vitro and in vivo studies on the use of MSCs in SLA. Electronic searching provided 45 titles, and among them, 8 papers were chosen as suitable based on the inclusion requirements of this review. The reviewed studies have revealed the potential of MSCs in SLA. According to these papers, stem cell therapy combined with different biomaterials may considerably improve bone regeneration in previous steps of dental implantation and may veritably lead to efficient clinical usages in the recent future. However, the identification of an ideal source of stem cells as well as long-term studies is vital to assess the success rate of this technology. Further clinical trials are also needed to approve the potential of MSCs in SLA.