Healing capacity of bone marrow mesenchymal stem cells versus platelet-rich fibrin in tibial bone defects of albino rats: an in vivo study

Standardization of Animal Models and Techniques for Platelet-Rich Fibrin Production: A Narrative Review and Guideline

Experimental research is critical for advancing medical knowledge and enhancing patient outcomes, including in vitro and in vivo preclinical assessments. Platelet-rich fibrin (PRF) is a blood by-product that has garnered attention in the medical and dental fields due to its potential for tissue regeneration and wound healing. Animal models, such as rabbits and rats, have been used to produce PRF and examine its properties and applications. PRF has demonstrated potential in the dental and medical fields for reducing inflammation, promoting tissue repair, and accelerating wound healing. This narrative review aims to compare existing evidence and provide guidelines for PRF animal research, emphasizing the importance of standardizing animal models, following ethical considerations, and maintaining transparency and accountability. The authors highlight the necessity to use the correct relative centrifugal force (RCF), standardize centrifugal calibration, and report detailed information about blood collection and centrifuge parameters for reproducible results. Standardizing animal models and techniques is crucial for narrowing the gap between laboratory research and clinical applications, ultimately enhancing the translation of findings from bench to bedside.

Evaluation of Autologously Derived Biomaterials and Stem Cells for Bone Tissue Engineering

Despite progress, clinical translation of tissue engineering (TE) products/technologies is limited. A significant effort is underway to develop biomaterials and cells through a minimally modified process for clinical translation of TE products. Recently, bone marrow aspirate (BMA) was identified as an autologous source of cells for TE applications and is currently being tested in clinical therapies, but the isolation methods need improvement to avoid potential for contamination and increase progenitor cell yield. To address these issues, we reproducibly processed human peripheral blood (PB) and BMA to develop autologously derived biomaterials and cells. We demonstrated PB-derived biomaterial/gel cross-linking and fibrin gel formation with varied gelation times as well as biocompatibility through support of human bone marrow-derived stem cell survival and growth in vitro. Next, we established a plastic culture-free process that concentrates and increases the yield of CD146+/CD271+ early mesenchymal progenitor cells in BMA (concentrated BMA [cBMA]). cBMA exhibited increased colony formation and multipotency (including chondrogenic differentiation) in vitro compared with standard BMA. PB-derived gels encapsulated with cBMA also demonstrated increased cell proliferation and enhanced mineralization when assessed for bone TE in vitro. This strategy can potentially be developed for use in any tissue regeneration application; however, bone regeneration was used as a test bed for this study.

Early therapeutic effect of platelet-rich fibrin combined with allogeneic bone marrow-derived stem cells on rats' critical-sized mandibular defects

BACKGROUND

Critically sized bone defects represent a significant challenge to orthopaedic surgeons worldwide. These defects generally result from severe trauma or resection of a whole large tumour. Autologous bone grafts are the current gold standard for the reconstruction of such defects. However, due to increased patient morbidity and the need for a second operative site, other lines of treatment should be introduced. To find alternative unconventional therapies to manage such defects, bone tissue engineering using a combination of suitable bioactive factors, cells, and biocompatible scaffolds offers a promising new approach for bone regeneration.

AIM

To evaluate the healing capacity of platelet-rich fibrin (PRF) membranes seeded with allogeneic mesenchymal bone marrow-derived stem cells (BMSCs) on critically sized mandibular defects in a rat model.

METHODS

Sixty-three Sprague Dawley rats were subjected to bilateral bone defects of critical size in the mandibles created by a 5-mm diameter trephine bur. Rats were allocated to three equal groups of 21 rats each. Group I bone defects were irrigated with normal saline and designed as negative controls. Defects of group II were grafted with PRF membranes and served as positive controls, while defects of group III were grafted with PRF membranes seeded with allogeneic BMSCs. Seven rats from each group were killed at 1, 2 and 4 wk. The mandibles were dissected and prepared for routine haematoxylin and eosin (HE) staining, Masson's trichrome staining and CD68 immunohistochemical staining.

RESULTS

Four weeks postoperatively, the percentage area of newly formed bone was significantly higher in group III (0.88 ± 0.02) than in groups I (0.02 ± 0.00) and II (0.60 ± 0.02). The amount of granulation tissue formation was lower in group III (0.12 ± 0.02) than in groups I (0.20 ± 0.02) and II (0.40 ± 0.02). The number of inflammatory cells was lower in group III (0.29 ± 0.03) than in groups I (4.82 ± 0.08) and II (3.09 ± 0.07).

CONCLUSION

Bone regenerative quality of critically sized mandibular bone defects in rats was better promoted by PRF membranes seeded with BMSCs than with PRF membranes alone.

Modeling trauma in rats: similarities to humans and potential pitfalls to consider

Trauma is the leading cause of mortality in humans below the age of 40. Patients injured by accidents frequently suffer severe multiple trauma, which is life-threatening and leads to death in many cases. In multiply injured patients, thoracic trauma constitutes the third most common cause of mortality after abdominal injury and head trauma. Furthermore, 40-50% of all trauma-related deaths within the first 48 h after hospital admission result from uncontrolled hemorrhage. Physical trauma and hemorrhage are frequently associated with complex pathophysiological and immunological responses. To develop a greater understanding of the mechanisms of single and/or multiple trauma, reliable and reproducible animal models, fulfilling the ethical 3 R's criteria (Replacement, Reduction and Refinement), established by Russell and Burch in 'The Principles of Human Experimental Technique' (published 1959), are required. These should reflect both the complex pathophysiological and the immunological alterations induced by trauma, with the objective to translate the findings to the human situation, providing new clinical treatment approaches for patients affected by severe trauma. Small animal models are the most frequently used in trauma research. Rattus norvegicus was the first mammalian species domesticated for scientific research, dating back to 1830. To date, there exist numerous well-established procedures to mimic different forms of injury patterns in rats, animals that are uncomplicated in handling and housing. Nevertheless, there are some physiological and genetic differences between humans and rats, which should be carefully considered when rats are chosen as a model organism. The aim of this review is to illustrate the advantages as well as the disadvantages of rat models, which should be considered in trauma research when selecting an appropriate in vivo model. Being the most common and important models in trauma research, this review focuses on hemorrhagic shock, blunt chest trauma, bone fracture, skin and soft-tissue trauma, burns, traumatic brain injury and polytrauma.

A cancellous bone matrix system with specific mineralisation degrees for mesenchymal stem cell differentiation and bone regeneration

Bone regenerative therapies have been explored using various biomaterial systems.