Plasma rich in growth factors (PRGF) for the promotion of bone cell proliferation and tissue regeneration

Stem cell-derived exosomes in bone healing: focusing on their role in angiogenesis

Fractures in bone, a tissue critical in protecting other organs, affect patients' quality of life and have a heavy economic burden on societies. Based on regenerative medicine and bone tissue engineering approaches, stem cells have become a promising and attractive strategy for repairing bone fractures via differentiation into bone-forming cells and production of favorable mediators. Recent evidence suggests that stem cell-derived exosomes could mediate the therapeutic effects of their counterpart cells and provide a cell-free therapeutic strategy in bone repair. Since bone is a highly vascularized tissue, coupling angiogenesis and osteogenesis is critical in bone fracture healing; thus, developing therapeutic strategies to promote angiogenesis will facilitate bone regeneration and healing. To this end, stem cell-derived exosomes with angiogenic potency have been developed to improve fracture healing. This review summarizes the effects of stem cell-derived exosomes on the repair of bone tissue, focusing on the angiogenesis process.

Preparation and In Vitro Osteogenic Evaluation of Biomimetic Hybrid Nanocomposite Scaffolds Based on Gelatin/Plasma Rich in Growth Factors (PRGF) and Lithium-Doped 45s5 Bioactive Glass Nanoparticles

Bone tissue engineering is an emerging technique for repairing large bone lesions. Biomimetic techniques expand the use of organic-inorganic spongy-like nanocomposite scaffolds and platelet concentrates. In this study, a biomimetic nanocomposite scaffold was prepared using lithium-doped bioactive-glass nanoparticles and gelatin/PRGF. First, sol-gel method was used to prepare bioactive-glass nanoparticles that contain 0, 1, 3, and 5%wt lithium. The lithium content was then optimized based on antibacterial and MTT testing. By freeze-drying, hybrid scaffolds comprising 5, 10, and 20% bioglass were made. On the scaffolds, human endometrial stem cells (hEnSCs) were cultured for adhesion (SEM), survival, and osteogenic differentiation. Alkaline phosphatase activity and osteopontin, osteocalcin, and Runx2 gene expression were measured. The effect of bioactive-glass nanoparticles and PRGF on nanocomposites' mechanical characteristics and glass-transition temperature (T _g) was also studied. An optimal lithium content in bioactive glass structure was found to be 3% wt. Nanoparticle SEM examination indicated grain deformation due to different sizes of lithium and sodium ions. Results showed up to 10% wt bioactive-glass and PRGF increased survival and cell adhesion. Also, Hybrid scaffolds revealed higher ALP-activity and OP, OC, and Runx2 gene expression. Furthermore, bioactive-glass has mainly increased ALP-activity and Runx2 expression, whereas PRGF increases the expression of OP and OC genes. Bioactive-glass increases scaffold modulus and T _g continuously. Hence, the presence of both bioactive-glass and nanocomposite scaffold improves the expression of osteogenic differentiation biomarkers. Subsequently, it seems that hybrid scaffolds based on biopolymers, Li-doped bioactive-glass, and platelet extracts can be a good strategy for bone repair.

Plasma rich in growth factors (PRGF) and leukocyte-platelet rich fibrin (L-PRF): comparative release of growth factors and biological effect on osteoblasts

PURPOSE

To compare the release of platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-I) and interleukin 1β (IL-1β) of plasma rich in growth factors (PRGF) and leucocyte platelet-rich fibrin (L-PRF) and to evaluate their biological implication in osteoblasts.

METHODS

Blood from 3 healthy volunteers was processed into PRGF, immediate L-PRF (L-PRF 0') and L-PRF 30 min after collection (L-PRF-30') and a control group. Growth factors release were analyzed at 7 times by ELISA. Cell proliferation, collagen-I synthesis and alkaline phosphatase activity were assessed in primary cultures of human osteoblasts.

RESULTS

A slower controlled release of IGF-I, VEGF and PDGF was observed in the PRGF group at day 14. A higher synthesis of type I collagen was also quantified in PRGF. L-PRF released significantly higher amounts of IL-1β, that was almost absent in the PRGF.

CONCLUSIONS

The addition of leukocytes dramatically increases the secretion of proinflammatory cytokines, which are likely to negatively influence the synthesis of type I collagen and alkaline phosphatase (ALP) by osteoblasts.

Dentin Growth after Direct Pulp Capping with the Different Fractions of Plasma Rich in Growth Factors (PRGF) vs. MTA: Experimental Study in Animal Model

Background: This study aimed to evaluate the area of dentin growth in rabbit incisors after pulp capping with plasma rich in growth factors (PRGF) compared with mineral trioxide aggregate (MTA) by fluorescence. Methods: twenty-seven upper and lower incisors of rabbits were divided into 4 groups: poor PRGF (F1) (n = 9 teeth), rich PRGF (F2) (n = 8 teeth), ProRoot MTA (positive control, n = 5 teeth), and untreated (NC) (negative control, n = 5). Fluorochrome markers were injected 24 h before surgery and the day before euthanasia, 28 days after the vital pulp therapy (VPT). Two transverse cuts were performed to every tooth: the first cut (A), 1 mm incisal to the gingival margin, and the second cut (B), 5 mm apical to the first cut. The sections were assessed with histomorphometric evaluation by fluorescence microscopy, comparing the dentin area between fluorescence marks and the total mineralized area. Results: The higher percentage of dentin growth was observed in the F2 group (B = 63.25%, A = 36.52%), followed by F1 (B = 57.63%, A = 30,12%) and MTA (B = 38.64%, A = 15.74%). The group with lowest percentage of dentin growth was the NC group (B = 29.22%, A = 7.82%). Significant difference (p < 0.05) was found between F2 group and MTA, also statistically significant difference has been observed comparing dentin growth areas of NC group with F1 and F2 groups. Conclusions: The application of PRGF rich and poor fraction as a pulp capping material stimulated dentin formation more intensively than MTA and NC.

An Injectable Fibrin Scaffold Rich in Growth Factors for Skin Repair

Platelet aggregates, such as PRP, PRF, and CGF, have been used alone or in combination with other grafting materials to enhance restoration outcomes. The process for preparing these autografting materials requires two-step centrifugation or specific centrifuges. In this study, we obtained an injectable fibrin scaffold (IFS) rich in growth factors by one-step centrifugation of whole blood from rabbits. The purpose of this study is to introduce some characteristics of IFS. This scaffold was characterized using various techniques, including Masson's trichrome staining, scanning electron microscopy, porosity measurements, and cell counting. The sustained release of growth factors, including PDGF, VEGF, TGF-β1, IGF, FGF, and EGF, was quantified using ELISA assay. The obtained IFS was tested for its effects on cell proliferation, extracellular matrix deposition, and full-thickness skin defect repair. The prepared IFS is characterized by a loose fibrin network structure with white blood cells and platelets that slowly release growth factors and can promote the healing of skin defects via the promotion of cell proliferation, collagen deposition, and tissue revascularization. In addition, its liquid properties and porous structure are conducive to its application as a therapeutic component in tissue engineering.

Simplified protocol for horizontal and vertical post-extractive GBR with intentionally exposed PTFE membrane - Case series

Purpose: Post-extractive sites often need soft and hard tissue regeneration in order to place implants with optimal functional and aesthetic conditions. The author proposed several techniques for bone preservation and regeneration: most of them requires release incisions and coronally advanced flap to obtain primary closure, so regain a correct alignment of keratinized gingiva makes mandatory a further surgery with a connective tissue graft from secondary surgical site. Case report: Since May 2018 we applied with some adjustments Open Barrier Technique (proposed by E. Funakoshi, 2005) in 152 post-extractive alveolar preservation and GBR; after 3-6 months we placed 194 implants, with 100% success and survival rate. Conclusions: Our simplified protocol allows performing vertical and horizontal GBR in post-extractive sites without release incisions: non resorbable PTFE membrane protects wound and bone graft for 6-8 week; secondary healing ensures thick keratinized tissue and bone maturation, suitable to place implants after 3-6 months.

Medical students' knowledge of medication related osteonecrosis of the jaw

INTRODUCTION

The objective of this study was to assess medical students' knowledge of "medication related osteonecrosis of the jaws" (MRONJ).

METHODS

A questionnaire survey was administered to all the medical students in the last two years of school of medicine at the University of Eastern Piedmont between January 2019 and March 2019. The questionnaire contained a first section regarding demographic and personal data of the student and a second section regarding the knowledge on MRONJ.

RESULTS

On the whole, 72 medical students agreed to participate to this study and filled in the questionnaire. As for indications for the use of bisphosphonates 45 students correctly answered "osteoporosis, osteogenesis imperfecta, multiple myeloma, or metastasis of some malignant tumors". Almost all students (71 out of 72) answered that a thorough examination of oral cavity and a dentist screening is needed and fundamental before starting bisphosphonate assumption. As for drugs responsible for MRONJ, only 12 students out of 72 correctly answered "bisphosphonates, denosumab, and antiangiogenic drugs".

DISCUSSION

A better level of knowledge and awareness by medical doctors and young physicians may lead, in future, to minimize incidence of MRONJ as well as to a better resolution of ONJ cases. Theoretical and practical initiatives could be promoted to improve and consolidate the knowledge of future physicians about this important issue.

Psychological profiles in patients undergoing orthognathic surgery or rhinoplasty: a preoperative and preliminary comparison

OBJECTIVE

The aim of this study was to assess, identify, and compare the personality traits and psychosocial status of two groups of patients undergoing orthognathic surgery and rhinoseptoplasty respectively.

STUDY DESIGN

This prospective study recruited patients referred for orthognathic surgery and for rhinoseptoplasty. The research protocol included the administrations of questionnaires to the patients during their last visit before surgery, including the Minnesota Multiphasic Personality Inventory (MMPI-2), the Myers-Briggs Type Indicator (MBTI), the tree drawing test (or Baum test), and the BC Scale.

RESULTS

As for MMPI-2, the highest (pathological) percentages were encountered in Hypochondriasis and Psychasthenia scales within the Orthognathic Surgery Group, whereas in the rhinoseptoplasty group, the highest scores were obtained in the Hypochondriasis, Psychasthenia, Psychopathic Deviate, and Schizophrenia scales.

CONCLUSIONS

It would be important to assess some characteristics of the patients' mental health and emotional state prior to surgery, including depression, anxiety, panic, and aggression. The overview of these factors may give an insight into the psychological and emotional capacity of the patients undergoing orthognathic and rhinoseptoplasty surgery.