Application of platelet-rich plasma in maxillofacial surgery: clinical evaluation

Methods and Limitations of Augmenting Mesenchymal Stem Cells for Therapeutic Applications

Significance: Given their capacity for self-renewal, multilineage differentiation, and immunomodulatory potential, mesenchymal stem cells (MSCs) represent a promising modality of clinical therapy for both regenerative medicine and immune diseases. In this study, we review the key approaches and popular methods utilized to boost potency and modify functions of MSCs for clinical purposes as well as their associated limitations. Recent Advances: Several major domains of cell modification strategies are currently employed by investigators to overcome these deficits and augment the therapeutic potential of MSCs. Priming MSCs with soluble factors or pharmacologic agents as well as manipulating oxygen availability in culture have been demonstrated to be effective biochemical methods to augment MSC potential. Distinct genetic and epigenetic methods have emerged in recent years to modify the genetic expression of target proteins and factors thereby modulating MSCs capacity for differentiation, migration, and proliferation. Physical methods utilizing three-dimensional culture methods and alternative cell delivery systems and scaffolds can be used to recapitulate the native MSC niche and augment their engraftment and viability for in vivo models. Critical Issues: Unmodified MSCs have demonstrated only modest benefits in many preclinical and clinical studies due to issues with cell engraftment, viability, heterogeneity, and immunocompatibility between donor and recipient. Furthermore, unmodified MSCs can have low inherent therapeutic potential for which intensive research over the past few decades has been dedicated to improving cell functionality and potency.

Platelet-rich plasma: a comparative and economical therapy for wound healing and tissue regeneration

Rise in the incidences of chronic degenerative diseases with aging makes wound care a socio-economic burden and unceasingly necessitates a novel, economical, and efficient wound healing treatment. Platelets have a crucial role in hemostasis and thrombosis by modulating distinct mechanistic phases of wound healing, such as promoting and stabilizing the clot. Platelet-rich plasma (PRP) contains a high concentration of platelets than naïve plasma and has an autologous origin with no immunogenic adverse reactions. As a consequence, PRP has gained significant attention as a therapeutic to augment the healing process. Since the past few decades, a robust volume of research and clinical trials have been performed to exploit extensive role of PRP in wound healing/tissue regeneration. Despite these rigorous studies and their application in diversified medical fields, efficacy of PRP-based therapies is continuously questioned owing to the paucity of large samplesizes, controlled clinical trials, and standard protocols. This review systematically delineates the process of wound healing and involvement of platelets in tissue repair mechanisms. Additionally, emphasis is laid on PRP, its preparation methods, handling, classification,application in wound healing, and PRP as regenerative therapeutics combined with biomaterials and mesenchymal stem cells (MSCs).

Platelet-Rich Plasma in Plastic Surgery: A Systematic Review

INTRODUCTION

Platelet-rich plasma (PRP) is gaining popularity and is applied in a variety of clinical settings. This review aims to present and evaluate available evidence regarding the use of PRP in various applications in plastic surgery.

METHODS

PubMed, Web of Science, Medline, and Embase were searched using predefined MeSH terms to identify studies concerning the application of PRP alone or in combination with fat grafting for plastic surgery. The search was limited to articles in English or German. Animal studies, in vitro studies, case reports, and case series were excluded.

RESULTS

Of 50 studies included in this review, eleven studies used PRP for reconstruction or wound treatment, eleven for cosmetic procedures, four for hand surgery, two for burn injuries, five for craniofacial disorders, and 17 as an adjuvant to fat grafting. Individual study characteristics were summarized. Considerable variation in preparation protocols and treatment strategies were observed. Even though several beneficial effects of PRP therapy were described, significance was not always demonstrated, and some studies yielded conflicting results. Efficacy of PRP was not universally proven in every field of application.

CONCLUSION

This study presents an overview of current PRP treatment options and outcomes in plastic surgery. PRP may be beneficial for some indications explored in this review; however, currently available data are insufficient and systematic evaluation is limited due to high heterogeneity in PRP preparation and treatment regimens. Further randomized controlled trials employing standardized protocols are warranted.

Effective high-throughput isolation of enriched platelets and circulating pro-angiogenic cells to accelerate skin-wound healing

Delayed wound healing and chronic skin lesions represent a major health problem. Over the past years, growth factors mediated by platelet-rich plasma (PRP) and cell-based therapies were developed as effective and affordable treatment able to improve wound healing capacity. We have advanced existing concepts to develop a highly efficient high-throughput protocol with proven application for the isolation of PRP and pro-angiogenic cells (Angio^PRP). This protocol outlines the effectiveness of Angio^PRP in promoting the critical healing process including wound closure, re-epithelialization, granulation tissue growth, and blood vessel regeneration. We coupled this effect with normalization of mechanical properties of rescued mouse wounds, which is sustained by a correct arrangement of elastin and collagen fibers. Proteomic analysis of treated wounds demonstrated a fingerprint of Angio^PRP based on the up-regulation of detoxification pathway of glutathione metabolism, correlated to a decrease in inflammatory response. Overall, these results have enabled us to provide a framework for how Angio^PRP supports wound healing, opening avenues for further clinical advances.

The Induced Membrane Technique—The Filling Matters: Evaluation of Different Forms of Membrane Filling with and without Bone Marrow Mononuclear Cells (BMC) in Large Femoral Bone Defects in Rats

The Masquelet technique is used to treat large bone defects; it is a two-stage procedure based on an induced membrane. To improve the induced membrane process, demineralized bone matrix in granular (GDBM) and fibrous form (f-DBM) was tested with and without bone marrow mononuclear cells (BMC) as filling of the membrane against the gold standard filling with syngeneic cancellous bone (SCB). A total of 65 male Sprague–Dawley rats obtained a 5 mm femoral defect. These defects were treated with the induced membrane technique and filled with SCB, GDBM, or f-DBM, with or without BMC. After a healing period of eight weeks, the femurs were harvested and submitted for histological, radiological, and biomechanical analyses. The fracture load in the defect zone was lower compared to SCB in all groups. However, histological analysis showed comparable new bone formation, bone mineral density, and cartilage proportions and vascularization. The results suggest that f-DBM in combination with BMC and the induced membrane technique cannot reproduce the very good results of this material in large, non-membrane coated bone defects, nevertheless it supports the maturation of new bone tissue locally. It can be concluded that BMC should be applied in lower doses and inflammatory cells should be removed from the cell preparation before implantation.

Cell and Cell Free Therapies in Osteoarthritis

Osteoarthritis (OA) is the most common articular disease in adults and has a current prevalence of 12% in the population over 65 years old. This chronic disease causes damage to articular cartilage and synovial joints, causing pain and leading to a negative impact on patients' function, decreasing quality of life. There are many limitations regarding OA conventional therapies-pharmacological therapy can cause gastrointestinal, renal, and cardiac adverse effects, and some of them could even be a threat to life. On the other hand, surgical options, such as microfracture, have been used for the last 20 years, but hyaline cartilage has a limited regeneration capacity. In recent years, the interest in new therapies, such as cell-based and cell-free therapies, has been considerably increasing. The purpose of this review is to describe and compare bioregenerative therapies' efficacy for OA, with particular emphasis on the use of mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP). In OA, these therapies might be an alternative and less invasive treatment than surgery, and a more effective option than conventional therapies.

Classification and coding of platelet-rich plasma derived from New Zealand white rabbits for tissue engineering and regenerative medicine applications

BACKGROUND AND OBJECTIVE

Platelet-rich plasma (PRP) is a category of platelet concentrate that has been widely used as a therapeutic modality in musculoskeletal medicine. The present study was conducted to classify and code the non-activated platelet-rich plasma (nPRP) derived from New Zealand white rabbits for tissue engineering and other regenerative medicine applications.

METHODS

PRP was prepared from the whole blood by double centrifugation protocol using a laboratory centrifuge. The prepared nPRP was characterized using the parameters such as platelet dose, the relative composition of platelets, WBC, and RBC. The production protocol was described using the parameters such as platelet enrichment factor, factor increase in WBC concentration, platelet capture efficiency, WBC-reducing efficiency, and RBC-reducing efficiency. The nPRP was also classified and coded using the most recent and universally accepted classification and coding systems.

RESULTS

The non-activated leukocyte-poor red cell-rich PRP had an average platelet count of 1875.75 × 10⁹/L, which is higher than the basal platelet concentration in the whole blood. Furthermore, the protocol used in this study has a mean platelet capture efficiency of 47.43 ± 6.42%.

CONCLUSION

The protocol described in this study can be used to prepare non-activated leukocyte-poor red cell-rich PRP (Red-PRP IC1) from rabbits that can be coded as 318-00-00.

Adipose mesenchymal stem cells combined with platelet-rich plasma accelerate diabetic wound healing by modulating the Notch pathway

Background

Diabetic foot ulceration is a serious chronic complication of diabetes mellitus characterized by high disability, mortality, and morbidity. Platelet-rich plasma (PRP) has been widely used for diabetic wound healing due to its high content of growth factors. However, its application is limited due to the rapid degradation of growth factors. The present study aimed to evaluate the efficacy of combined adipose-derived mesenchymal stem cells (ADSCs) and PRP therapy in promoting diabetic wound healing in relation to the Notch signaling pathway.

Methods

Albino rats were allocated into 6 groups [control (unwounded), sham (wounded but non-diabetic), diabetic, PRP-treated, ADSC-treated, and PRP+ADSCs-treated groups]. The effect of individual and combined therapy was evaluated by assessing wound closure rate, epidermal thickness, dermal collagen, and angiogenesis. Moreover, gene and protein expression of key elements of the Notch signaling pathway (Notch1, Delta-like canonical Notch ligand 4 (DLL4), Hairy Enhancer of Split-1 (Hes1), Hey1, Jagged-1), gene expression of angiogenic marker (vascular endothelial growth factor and stromal cell-derived factor 1) and epidermal stem cells (EPSCs) related gene (ß1 Integrin) were assessed.

Results

Our data showed better wound healing of PRP+ADSCs compared to their individual use after 7 and 14 days as the combined therapy caused reepithelialization and granulation tissue formation with a marked increase in area percentage of collagen, epidermal thickness, and angiogenesis. Moreover, Notch signaling was significantly downregulated, and EPSC proliferation and recruitment were enhanced compared to other treated groups and diabetic groups.

Conclusions

These data demonstrated that PRP and ADSCs combined therapy significantly accelerated healing of diabetic wounds induced experimentally in rats via modulating the Notch pathway, promoting angiogenesis and EPSC proliferation.

Bone Grafts and Substitutes in Dentistry: A Review of Current Trends and Developments

After tooth loss, bone resorption is irreversible, leaving the area without adequate bone volume for successful implant treatment. Bone grafting is the only solution to reverse dental bone loss and is a well-accepted procedure required in one in every four dental implants. Research and development in materials, design and fabrication technologies have expanded over the years to achieve successful and long-lasting dental implants for tooth substitution. This review will critically present the various dental bone graft and substitute materials that have been used to achieve a successful dental implant. The article also reviews the properties of dental bone grafts and various dental bone substitutes that have been studied or are currently available commercially. The various classifications of bone grafts and substitutes, including natural and synthetic materials, are critically presented, and available commercial products in each category are discussed. Different bone substitute materials, including metals, ceramics, polymers, or their combinations, and their chemical, physical, and biocompatibility properties are explored. Limitations of the available materials are presented, and areas which require further research and development are highlighted. Tissue engineering hybrid constructions with enhanced bone regeneration ability, such as cell-based or growth factor-based bone substitutes, are discussed as an emerging area of development.

AIRMESS - Academy of International Regenerative Medicine & Surgery Societies: recommendations in the use of platelet-rich plasma (PRP), autologous stem cell-based therapy (ASC-BT) in androgenetic alopecia and wound healing

INTRODUCTION

Many investigations showed that platelet-rich plasma (PRP), human follicles stem cells (HFSCs), and adipose-derived stem cells (ASCs), considered autologous stem cell-based therapy (ASC-BT), are effective for hair regrowth (HR) in patients affected by androgenetic alopecia and for wound healing (WH). The aim of this article is to analyze the in vitro and in vivo impact of different PRP, HFSCs, and ASCs preparation methods on HR and in WH.

AREAS COVERED

The analyzed data intended to clarify the molecular mechanism in which PRP, HFSCs, and ASCs are involved, the clinical use and related indications, fully respecting the European rules. Comparative studies between different systems of PRP, HFSCs, and ASCs preparation revealed differences in terms of HR and WH.

EXPERT OPINION

Despite a lack of standardized protocols, there is convincing evidence with objective measurement modalities that display positive outcomes of ASC-BT in HR and WH.

Level of Evidence on Platelet-rich Plasma in Plastic Surgery

BACKGROUND

Despite the increased popularity of platelet-rich plasma (PRP) in plastic surgery, there is no detailed analysis on the level of evidence on PRP use in plastic surgery. As the number of applications of PRP in plastic surgery increases, it is important for plastic surgeons to understand the scientific and validated evidence behind its use. Therefore, we performed a literature review to identify current level of evidence on platelet-rich plasma in plastic surgery.

METHODS

We performed a computerized search of platelet-rich plasma in plastic surgery using the MEDLINE, Cochran Library, and EMBASE databases. Data regarding the type of study, PRP application, and outcomes were collected. Then, the level of evidence was assigned using the American Society of Plastic Surgeons Level of Evidence Rating.

RESULTS

Our search identified 105 articles, and about 78.1% of studies were lower-quality studies: 37 level-III articles (35.2%), 32 level-IV articles (30.5%), and 13 level-V articles (12.4%). There were only 6 level-I articles and 17 level-II studies. Level-I studies were on facial rejuvenation using a laser, carpal tunnel release, cleft lip repair, trauma wounds, breast reconstruction using latissimus dorsi, and hair regrowth.

CONCLUSIONS

Our review of the literature shows that the level of evidence on PRP use in plastic surgery is low (21.9%). Nevertheless, we believe level-III to level-V studies are still valuable, as performing high-level quality studies in plastic surgery is difficult due to variability in surgical techniques, experiences, and materials.

Platelet rich plasma in oral and maxillofacial surgery from the perspective of composition

The application of platelet-rich plasma (PRP) in oral and maxillofacial surgery has been thoroughly studied in the last two decades. Currently, different types of PRP are applied in the clinical practice, being the presence or absence of leukocytes one of the classification criteria. However, there is poor evidence assessing the influence of the PRP composition in their efficacy. In this context, the aim of this narrative review is to compile the existing evidence covering the efficacy of PRP in oral and maxillofacial surgery, starting from a systematic literature search and to qualitatively describe the efficacy outcomes from the composition perspective. According to the results of this review, the application of PRP in oral and maxillofacial surgery is a potential strategy to improve soft- and hard-tissue regeneration, observing differences in the efficacy of PRP depending on its composition and the studied application. P-PRP (the absence of leukocytes) has been more consistent in achieving beneficial effects in alveolar ridge preservation, management of post-extraction complications, bone augmentation and temporomandibular joint disorders. For that, the composition and methodology used to prepare the PRP should be a critical point when evaluating the efficacy of PRP.

Application of platelet-rich plasma in traumatic bone infections

Introduction: Traumatic bone infection represents a clinical challenge for orthopedic surgeons. Traditional treatments include surgical debridement and antibiotic, but prolonged use of antibiotic may lead to colonization of resistant bacteria and other adverse reactions.Areas covered: Platelet-rich plasma (PRP), a biological product extracted from the peripheral blood of patients, has been widely used in the field of tissue repair in recent years. Because if its structural and antibacterial properties, PRP is an innovative option for the prevention and treatment of infections. This review assesses the recent scientific literature on PRP, specifically its in the treatment of infections. To this end, a literature review was conducted using the PubMed and Web of Science databases with the following keywords 'platelet-rich plasma (PRP)'; 'PRP AND traumatic bone infections'; 'PRP AND bone defect'; 'PRP AND antibiotics'; and 'PRP AND wound healing'.Expert opinion: This review focuses on the mechanism of action, preparation methods, clinical applications and other aspects related to PRP to provide a reference for its use in the treatment of traumatic bone infections, thereby enhancing the therapeutic effectiveness and improving the prognosis of patients.

DNMT1-mediated methylation inhibits microRNA-214-3p and promotes hair follicle stem cell differentiate into adipogenic lineages

Background

Dysfunction of the DNA methylation was associated with stem cell reprogramming. Moreover, DNA methyltransferase 1 (DNMT1) deficiency was involved in the differentiation of hair follicle stem cell (HFSc), but the molecular mechanisms remain unknown.

Methods

HFSc from human scalp tissues were isolated and cultured. The oil red O staining was used to observe the adipogenesis. The interaction relationship between microRNA (miR)-214-3p and mitogen-activated protein kinase 1 (MAPK1) was accessed by dual-luciferase reporter gene assay. The methylation level of miR-214-3p promoter was detected by methylation-specific PCR and the enrichment of DNMT1 in miR-214-3p promoter by chromatin immunoprecipitation assay. A mouse model of trauma was established to observe the skin regeneration at 0, 6, and 14 days.

Results

Expression of DNMT1 and MAPK1 was increased in the HFSc, while the expression of miR-214-3p was reduced. Moreover, DNMT1 inhibited the expression of miR-214-3p by promoting the promoter methylation of miR-214-3p. Overexpression of DNMT1 could reduce the expression of miR-214-3p, but increase the expression of MAPK1 and the extent of extracellular signal regulated kinase (ERK)1/2 phosphorylation, leading to enhanced adipogenic differentiation. Importantly, DNMT1 promoted skin regeneration in vivo. Conversely, overexpression of miR-214-3p could reverse the effects of DNMT1 on adipogenesis of HFSc.

Conclusion

DNMT1 promotes adipogenesis of HFSc by mediating miR-214-3p/MAPK1/p-ERK1/2 axis. This study may provide novel biomarkers for the potential application in stem cell therapy.

Hair follicle bulge-derived stem cells promote tissue regeneration during skin expansion

Skin expansion is widely used in reconstructive surgery to obtain supplemental and optimal skin. Enhancing the regenerative capacity of expanded skin is therefore of great interest. Hair follicle bulge-derived stem cells (HFBSCs) located in hair follicle bulges are closely associated with skin; HFBSC transplantation could promote cutaneous wound repair. However, the effects of transplanted HFBSCs on skin regeneration during expansion remain unclear. The aim of the study was to reveal the potential effects of transplanted HFBSCs in the expanded skin and explore its mechanism. Our results showed higher skin area, tissue weight, epidermal thickness, dermal thickness, proliferating cell count, collagen content, microcirculatory blood flow, blood vessels, and lower retraction ratios were observed in HFBSC-injected rats compared to uninjected controls. Moreover, the transplanted HFBSCs directly contributed to tissue regeneration by differentiating into vascular endothelial cells, epidermal cells, and the outer root sheath cells of hair follicle. Higher expression of EGF, VEGF, bFGF, and TGF-β were observed in HFBSC-injected rats. Our research demonstrated the transplanted HFBSCs could promote skin regeneration by differentiating into various types of skin related cells and by up-regulating the expression of growth factors. Our results could form a basis for the development of novel strategies to enhance regeneration in expanded skin by using HFBSCs.

Examination of androgenetic alopecia with serum biomarkers

BACKGROUND

Androgenetic alopecia (AGA) is the most common type of hair loss and affects approximately 50% of the male population.

AIMS

In the present study, to investigate microinflammation, perifollicular fibrosis, and oxidative stress in AGA cases, some serum biomarker levels were measured and evaluated.

PATIENTS/METHODS

Serum samples were drawn from patients (n = 58) and control (n = 30) groups referring to Atatürk Training and Investigation Hospital Dermatology Outpatient clinic. In serum samples, NF-κB, TNF-α, TGF-β1, thioredoxin, nitric oxide, TOS, TAS, and thiol disulfide homeostasis (native thiol, total thiol, disulfide) were measured and evaluated.

RESULTS

In patients with AGA, NF-κB (P = .005), TNF-α (P = .008), TGF-β1 (P = .028), thioredoxin (P = .004), nitric oxide (P < .001), and TOS (P < .001) serum levels were found to be significantly higher than those in control group, while TAS (P = .003), native thiol (P < .001), total thiol (P < .001), and disulfide (P < .001) serum levels were found to be significantly lower.

CONCLUSIONS

According to the results of the present study, it was concluded that in that AGA androgens lead to oxidative stress by increasing free oxygen radicals, which accelerates hair loss by causing microinflammation and fibrosis. The recognition of the effect of androgens and associated factors on the hair follicle cycle is essential for the development of new and effective treatment methods.

Efficacy assessment of mesenchymal stem cell transplantation for burn wounds in animals: a systematic review

Background

Clinically, severe burns remain one of the most challenging issues, but an ideal treatment is yet absent. Our purpose is to compare the efficacy of stem cell therapy in a preclinical model of burn wound healing.

Methods

Research reports on mesenchymal stem cells (MSCs) for burn wound healing were retrieved from 5 databases: PubMed, Embase, MEDLINE, Web of Science, and the Cochrane Library. The primary outcomes reported in this article include the un-healing rate of the wound area, the closure rate, and the wound area. Secondary outcomes included CD-31, vascular density, interleukin (IL)-10, thickness of eschar tissue, vascular endothelial growth factor (VEGF), and white blood cell count. Finally, a subgroup analysis was conducted to explore heterogeneity that potentially impacted the primary outcomes. A fixed-effects model with a 95% confidence interval (CI) was performed when no significant heterogeneity existed. Otherwise, a random-effects model was used. All data analysis was conducted by using Engauge Digitizer 10.8 and R software.

Results

Twenty eligible articles were finally included in the analysis. Stem cell therapy greatly improved the closure rate (2.00, 95% CI 0.52 to 3.48, p = 0.008) and compromised the wound area (− 2.36; 95% CI − 4.90 to 0.18; p = 0.069) rather than the un-healing rate of the wound area (− 11.10, 95% CI − 32.97 to 10.78, p = 0.320). Though p was 0.069, there was a trend toward shrinkage of the burn wound area after stem cell therapy. Vascular density (4.69; 95% CI 0.06 to 9.31; p = 0.047) and thickness of eschar tissue (6.56, 95% CI 1.15 to 11.98, p = 0.017) were also discovered to be significantly improved in the burn site of stem cell-treated animals. Moreover, we observed that animals in the stem cell group had an increased white blood cell count (0.84, 95% CI 0.01 to 1.66, p = 0.047) 5 days post treatment. Other indicators, such as VEGF (p = 0.381), CD-31 (p = 0.335) and IL-10 (p = 0.567), were not significantly impacted.

Conclusions

Despite limited data from preclinical trials, this meta-analysis suggests that stem cell therapy is curative in decreasing the burn wound area and provides some insights into future clinical studies of stem cell therapy for burns.

3D co-culture model of endothelial colony-forming cells (ECFCs) reverses late passage adipose-derived stem cell senescence for wound healing

Background

Extensive passage of adipose-derived stem cells (ASCs) in vitro leads to loss of function. Endothelial colony-forming cells (ECFCs) can be isolated from adult peripheral blood. A 3D co-culture system may rescue in vitro ASC senescence.

Methods

A 3D co-culture model was successfully established using hyaluronic acid (HA) gel and a 10:1 ratio of late-passage ASCs and ECFCs. Cell density and culture conditions were optimized. Stem cell phenotype was characterized by flow cytometry. ELISA was used to measure the trophic effect of angiogenic growth factors and compare the effects of these factors between the 3-D co-culture and single-cell culture. Therapeutic potential of ASC/ECFC 3-D co-cultures was evaluated in a mouse chronic injury model.

Results

Following incubation in a HA substrate 3D co-culture system, ASC morphology, phenotype, secretory profile, and differentiation capacity were restored. The ASC/ECFC co-culture increased the secretion of cytokines, such as hepatocyte growth factor, compared with single-cell 3D culture or monolayer culture. Mice radiation-ulcer wounds treated with ASC/ECFC 3-D co-cultures (spheroids) showed epithelialization and improved healing compared with wounds treated with ASCs or ECFCs alone. Further, transplanted ASC/ECFC spheroids exhibited superior angiogenic potential due to the ability of the ASCs to transdifferentiate into pericytes.

Conclusion

3D co-culture of ECFCs and ASCs in vitro restored native ASC properties by reversing cellular senescence and loss of trophic function. Transplant of ASC/ECFC 3D spheroids in vivo demonstrated pro-angiogenic capacity with improved therapeutic potential.

Systematic Review-The Potential Implications of Different Platelet-Rich Plasma (PRP) Concentrations in Regenerative Medicine for Tissue Repair

The number of studies evaluating platelet-rich plasma (PRP) concentration has substantially grown in the last fifteen years. A systematic review on this field has been realized by evaluating in the identified studies the in vitro PRP concentration—also analyzing the platelet amount—and the in vivo PRP effects in tissue regeneration compared to any control. The protocol has been developed in agreement with the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. Multistep research of the PubMed, MEDLINE, Embase, PreMEDLINE, Ebase, CINAHL, PsycINFO, Clinicaltrials.gov, Scopus database and Cochrane databases has permitted to identify articles on different concentrations of PRP in vitro and related in vivo impact for tissue repair. Of the 965 articles initially identified, 30 articles focusing on PRP concentration have been selected and, consequently, only 15 articles have been analyzed. In total, 40% (n = 6) of the studies were related to the fixed PRP Concentration Group used a fixed PRP concentration and altered the platelet concentration by adding the different volumes of the PRP (lysate) to the culture. This technique led to a substantial decrease in nutrition available at higher concentrations. Sixty percent (n = 9) of the studies were related to the fixed PRP Volume Group that used a fixed PRP-to-media ratio (Vol/Vol) throughout the experiment and altered the concentration within the PRP volume. For both groups, when the volume of medium (nutrition) decreases, a lower rate of cell proliferation is observed. A PRP concentration of 1.0 × 10⁶ plt/μL, appears to be optimal thanks to the constant and plentiful capillary nutrition supply and rapid diffusion of growth factors that happen in vivo and it also respects the blood decree-law. The PRP/media ratio should provide a sufficient nutrition supply to prevent cellular starvation, that is, PRP ≤ 10% (Vol/Vol) and thus best mimic the conditions in vivo.

A randomized blinded retrospective study: the combined use of micro-needling technique, low-level laser therapy and autologous non-activated platelet-rich plasma improves hair re-growth in patients with androgenic alopecia

INTRODUCTION

Mini-invasive therapies based on autologous non-activated Platelet-Rich Plasma (ANA-PRP), Low-Level Laser Therapy (LLL-T), and Micro-Needling Technique (MN-T) used in combining for hair re-growth need to be standardized.

OBJECTIVES

The work aims to show in vivo outcomes resulted from retrospective case-series study in which ANA-PRP + MN-T + LLL-T were used in combined in patients affected by Androgenic alopecia.

METHODS

23 patients were treated, of which 13 males were classified in stage I-V by the Norwood-Hamilton scale, and 10 females were classified in stage I-III by the Ludwig scale. Assessment of hair re-growth was evaluated with photography, physician's and patient's global assessment scale, and standardized phototrichograms during a follow-up: T0 - baseline, T1 - 12 weeks, T2 - 23 weeks, T3 - 44 weeks, T4 - 58 weeks.

RESULTS

Interesting outcomes represented by a hair density increase of 81 ± 5 hairs/cm² and 57 ± 7 hairs/cm² respectively at T1 and T2 compared with baseline (173 ± 5 hairs/cm² at T1 and 149 ± 9 hairs/cm² at T2 versus 92 ± 2 hairs/cm² at baseline) were observed using computerized trichograms.

EXPERT OPINION

The main limitation in the autologous regenerative therapies and biotechnologies in hair-regrowth is the extreme variability of PRP products used, in the absence of standardized protocols and widely shared. Appropriate PRP preparations have to be pick after carefully thinking about their bio-molecular specifications and intended indications for use in patients. This approach will aid in matching the optimal PRP product to specific patient factors, leading to improved outcomes and the elucidation of the cost-effectiveness of this treatment. The combined use of biotechnologies as the association of PRP with micro-needling and low-level laser therapy may improve the results in terms of hair count and hair density compared with those obtained by alone PRP. All the procedures must be performed in the full respect of international and local rules.

CONCLUSIONS

The effect of the combined use of MN-T, LLL-T, and ANA-PRP has been demonstrated.

Multiomics global landscape of stemness-related gene clusters in adipose-derived mesenchymal stem cells

Background

Adipose-derived mesenchymal stem cells (AD-MSCs) are a type of stem cell that is abundant and widely used. The molecular characteristics of AD-MSCs from different passages from donors of different ages have not been well elucidated.

Methods

Six kinds of AD-MSCs ((E1, E2, E3, Y1, Y2, and Y3) with E denoting cells derived from an elderly patient, Y denoting cells derived from a young patient, and 1, 2, and 3 representing passages 3, 6, and 10) were obtained from human abdominal adipose tissue. We obtained the protein expression profile, the mRNA expression profile, the lncRNA expression profile, and the methylation profile of each kind of AD-MSC by sequencing. After calculating the stemness indices, genes related to stemness were extracted. The multiomics correlation analysis was performed in the stemness-related genes. In addition, short time-series expression miner (STEM) analysis was performed for all cell passages and donor ages. To further explore the biological functions of the stemness-related genes, we performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Finally, the lncRNA-KEGG network and transcription factor (TF)-KEGG network were constructed based on the RNAInter database and TRRUST v2 database.

Results

The stemness of the Y1, E1, and Y2 cells was higher than that of the E2, Y3, and E3 cells. The stemness was the highest for Y1 cells and the lowest for E3 cells. STEM analysis showed that five stemness-related gene clusters were associated with the cell passages, and only one gene cluster was associated with age. The enrichment analysis results showed that the biological processes (BPs) and KEGG pathways were mainly involved in the proliferation, differentiation, and migration of cells. The global regulatory landscape of AD-MSCs was constructed: 25 TFs and 16 lncRNAs regulated 21 KEGG pathways through 27 mRNAs. Furthermore, we obtained a core stemness-related gene set consisting of ITGAV, MAD2L1, and PCNA. These genes were expressed at higher levels in Y1 cells than in E3 cells.

Conclusion

The multiomics global landscape of stemness-related gene clusters was determined for AD-MSCs, which may be helpful for selecting AD-MSCs with increased stemness.

Human bone marrow mesenchymal stem cell-derived exosomes stimulate cutaneous wound healing mediates through TGF-β/Smad signaling pathway

BACKGROUND

Cutaneous wound healing represents a morphogenetic response to injury and is designed to restore anatomic and physiological function. Human bone marrow mesenchymal stem cell-derived exosomes (hBM-MSC-Ex) are a promising source for cell-free therapy and skin regeneration.

METHODS

In this study, we investigated the cell regeneration effects and its underlying mechanism of hBM-MSC-Ex on cutaneous wound healing in rats. In vitro studies, we evaluated the role of hBM-MSC-Ex in the two types of skin cells: human keratinocytes (HaCaT) and human dermal fibroblasts (HDFs) for the proliferation. For in vivo studies, we used a full-thickness skin wound model to evaluate the effects of hBM-MSC-Ex on cutaneous wound healing in vivo.

RESULTS

The results demonstrated that hBM-MSC-Ex promote both two types of skin cells' growth effectively and accelerate the cutaneous wound healing. Interestingly, we found that hBM-MSC-Ex significantly downregulated TGF-β1, Smad2, Smad3, and Smad4 expression, while upregulated TGF-β3 and Smad7 expression in the TGF-β/Smad signaling pathway.

CONCLUSIONS

Our findings indicated that hBM-MSC-Ex effectively promote the cutaneous wound healing through inhibiting the TGF-β/Smad signal pathway. The current results provided a new sight for the therapeutic strategy for the treatment of cutaneous wounds.

A randomized, double-blind, vehicle-controlled clinical study of hair regeneration using adipose-derived stem cell constituent extract in androgenetic alopecia

Accumulating evidence suggests that adipose‐derived stem cell constituent extract (ADSC‐CE) helps hair regrowth in patients with androgenetic alopecia (AGA). However, the effects of ADSC‐CE have not been demonstrated in a randomized, double‐blind, vehicle‐controlled clinical trial. In this randomized, double‐blind, vehicle‐controlled clinical trial, 38 patients (29 men) with AGA were assigned to an intervention group (IG), with twice‐daily self‐application of the ADSC‐CE topical solution over the scalp with fingers, or to a control group (CG). Changes in hair count and thickness at 16 weeks from the baseline were evaluated using a phototrichogram. Overall, 34 (89%) patients (mean age, 45.3 years) completed the study. The phototrichogram at week 8 showed more increase in hair count in the IG than in the CG, and intergroup differences in the change of hair count remained significant until week 16 with overall changes of 28.1% vs 7.1%, respectively. Similarly, a significant improvement in hair diameter was observed in the IG (14.2%) after 16 weeks when compared with hair diameter in the CG (6.3%). Our findings suggest that the application of the ADSC‐CE topical solution has enormous potential as an alternative therapeutic strategy for hair regrowth in patients with AGA, by increasing both hair density and thickness while maintaining adequate treatment safety.

rAAV-Mediated Overexpression of SOX9 and TGF-β via Carbon Dot-Guided Vector Delivery Enhances the Biological Activities in Human Bone Marrow-Derived Mesenchymal Stromal Cells

Scaffold-assisted gene therapy is a highly promising tool to treat articular cartilage lesions upon direct delivery of chondrogenic candidate sequences. The goal of this study was to examine the feasibility and benefits of providing highly chondroreparative agents, the cartilage-specific sex-determining region Y-type high-mobility group 9 (SOX9) transcription factor or the transforming growth factor beta (TGF-β), to human bone marrow-derived mesenchymal stromal cells (hMSCs) via clinically adapted, independent recombinant adeno-associated virus (rAAV) vectors formulated with carbon dots (CDs), a novel class of carbon-dominated nanomaterials. Effective complexation and release of a reporter rAAV-lacZ vector was achieved using four different CDs elaborated from 1-citric acid and pentaethylenehexamine (CD-1); 2-citric acid, poly(ethylene glycol) monomethyl ether (MW 550 Da), and N,N-dimethylethylenediamine (CD-2); 3-citric acid, branched poly(ethylenimine) (MW 600 Da), and poly(ethylene glycol) monomethyl ether (MW 2 kDa) (CD-3); and 4-citric acid and branched poly(ethylenimine) (MW 600 Da) (CD-4), allowing for the genetic modification of hMSCs. Among the nanoparticles, CD-2 showed an optimal ability for rAAV delivery (up to 2.2-fold increase in lacZ expression relative to free vector treatment with 100% cell viability for at least 10 days, the longest time point examined). Administration of therapeutic (SOX9, TGF-β) rAAV vectors in hMSCs via CD-2 led to the effective overexpression of each independent transgene, promoting enhanced cell proliferation (TGF-β) and cartilage matrix deposition (glycosaminoglycans, type-II collagen) for at least 21 days relative to control treatments (CD-2 lacking rAAV or associated to rAAV-lacZ), while advantageously restricting undesirable type-I and -X collagen deposition. These results reveal the potential of CD-guided rAAV gene administration in hMSCs as safe, non-invasive systems for translational strategies to enhance cartilage repair.

Systematic Review of Platelet-Rich Plasma Use in Androgenetic Alopecia Compared with Minoxidil®, Finasteride®, and Adult Stem Cell-Based Therapy

The number of articles evaluating platelet-rich plasma (PRP) efficacy in androgenic alopecia (AGA) have exponentially increased during the last decade. A systematic review on this field was performed by assessing in the selected studies the local injections of PRP compared to any control for AGA. The protocol was developed in accordance with the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. A multistep search of the PubMed, MEDLINE, Embase, PreMEDLINE, Ebase, CINAHL, PsycINFO, Clinicaltrials.gov, Scopus database, and Cochrane databases was performed to identify studies on hair loss treatment with platelet-rich plasma. Of the 163 articles initially identified, 123 articles focusing on AGA were selected and, consequently, only 12 clinical trials were analyzed. The studies included had to match predetermined criteria according to the PICOS (patients, intervention, comparator, outcomes, and study design) approach. In total, 84% of the studies reported a positive effect of PRP for AGA treatment. Among them, 50% of the studies demonstrated a statistically significant improvement using objective measures and 34% of the studies showed hair density and hair thickness improvement, although no p values or statistical analysis was described. In total, 17% of the studies reported greater improvement in lower-grade AGA, while 8% noted increased improvement in higher-grade AGA. Only 17% of the studies reported that PRP was not effective in treating AGA. The information analyzed highlights the positive effects of PRP on AGA, without major side effects and thus it be may considered as a safe and effective alternative procedure to treat hair loss compared with Minoxidil^® and Finasteride^®.

Platelet-rich plasma and regenerative dentistry

Regenerative dentistry is an emerging field of medicine involving stem cell technology, tissue engineering and dental science. It exploits biological mechanisms to regenerate damaged oral tissues and restore their functions. Platelet‐rich plasma (PRP) is a biological product that is defined as the portion of plasma fraction of autologous blood with a platelet concentration above that of the original whole blood. A super‐mixture of key cytokines and growth factors is present in platelet granules. Thus, the application of PRP has gained unprecedented attention in regenerative medicine. The rationale underlies the utilization of PRP is that it acts as a biomaterial to deliver critical growth factors and cytokines from platelet granules to the targeted area, thus promoting regeneration in a variety of tissues. Based on enhanced understanding of cell signalling and growth factor biology, researchers have begun to use PRP treatment as a novel method to regenerate damaged tissues, including liver, bone, cartilage, tendon and dental pulp. To enable better understanding of the regenerative effects of PRP in dentistry, this review describes different methods of preparation and application of this biological product, and provides detailed explanations of the controversies and future prospects related to the use of PRP in dental regenerative medicine.

Macroporous elastic cryogels based on platelet lysate and oxidized dextran as tissue engineering scaffold: In vitro and in vivo evaluations

In this study, three-dimensional macroporous cryogels were developed from platelet lysate (PL) and different concentrations of oxidized dextran (OD; 0.5, 1, 2, 4%). Subsequently, PL/OD scaffolds were characterized for potential use in tissue engineering applications. The pore size and morphology of the resulting cryogels were visualized using scanning electron microscopy (SEM). The pore size distributions were determined using mercury intrusion porosimetry (MIP). In vitro hydrolytic degradation, water uptake, mechanical properties and hemocompatibility were investigated. Extraction test was carried out to evaluate potential in vitro toxic effects of the PL/OD. The in vitro adhesion, proliferation, chondrogenic differentiation, and extracellular matrix production of human adipose stem cells (hASCs) on PL/OD cryogels were evaluated. In vivo biodegradation of the cryogels was investigated at the subcutaneous dorsal site of rats. SEM and MIP results indicated that PL/OD had a macroporous pore structure with pore sizes ranging between 10 and 200 μm. The cryogels completely degraded within 90-240 days post-implantation, depending on OD concentration. Histochemical analysis revealed high levels of cell and tissue infiltration into the pores of PL/OD. In vitro cytotoxicity findings indicated that the extracts of PL/OD_0.5, PL/OD₁ and PL/OD₂ showed no cytotoxic effect, whereas that of PL/OD₄ exhibited a moderate cytotoxic effect on cell cultures. hASCs seeded on PL/OD₂ retained their viability and showed extensive spreading and filopodia formation after 7 days. PL/OD₂ also supported the chondrogenesis of hASCs in the presence of chondro-inductive factors. Given all the results, PL/OD could have potential as a scaffold for tissue engineering applications.

Impact of the Different Preparation Methods to Obtain Autologous Non-Activated Platelet-Rich Plasma (A-PRP) and Activated Platelet-Rich Plasma (AA-PRP) in Plastic Surgery: Wound Healing and Hair Regrowth Evaluation

Autologous therapies using platelet-rich plasma (PRP) need meticulous preparation—currently, no standardised preparation technique exists. Processing Quantitative Standards (PQSs) define manufacturing quantitative variables (such as time, volume and pressure). Processing Qualitative Standards (PQLSs) define the quality of the materials and methods of manufacturing. The aim of this review is to use existing PQSs and PQLs to report the in vivo/in vitro results obtained by using different Kits, that utilise different procedures (classified as Closed-Technique and Opened-Technique) to isolate autologous human activated (AA-PRP) or non-activated PRP (A-PRP). PQSs included the volumes of blood collected as well as the reagents used, the time/gravity of centrifugation, and the duration, temperature and tilt level/speed of centrifugation. PQLSs included the use of Calcium Chloride CaCl_2, Kit weight, transparency of Kit components, the maintenance of a closed sterile processing environment and the use of a small centrifuge. Eight CE marked devices for PRP extraction were evaluated: Angel^®, Biomed^®, Cascade^® and Selphyl^®, Mag-18^®, i-Stem^®, MyCells^® and Regenlab^®. Using a Kit with the PQSs and PQLSs described in this study enables the isolation of A-PRP, thereby meeting consensus quality criteria. As our understanding of Critical Quality Attributes (CQAs) of A-PRP continues to evolve, especially with respect to purity and potency, adjustments to these benchmark PQSs and PQLs will hopefully help isolate A-PRP of desired CQAs with greater reproducibility, quality, and safety. Confirmatory studies will no doubt need to be completed.

Platelet-derived bio-products: Classification update, applications, concerns and new perspectives

Platelet derived bio-products in the form of platelet rich plasma, plasma rich in growth factors, or plasma-free platelet releasates, are being studied worldwide with the aim of proving their efficacy in tissue regeneration within many different clinical areas, such as traumatology, maxillofacial surgery, ophthalmology, dermatology and otorhinolaryngology, amongst others. The current lack of consensus in the preparation method and application form, or in the quality assessment of each bio-product, precludes adequate interpretation of the relevance of reported clinical outcomes, and, while many in clinicians are very positive about them, many are sceptic. Relevant aspects of these products are considered to propose a classification nomenclature which would aid a comprehensive comparison of clinical outcomes of bio-products of the same characteristics. Finally, the uses of platelet-derived bio-products in in vitro culture (for cell therapy purposes) as a substitute of animal-origin sera, and other future perspectives of applications of platelet-derived bio-products are discussed.

Impact of the Different Preparation Methods to Obtain Human Adipose-Derived Stromal Vascular Fraction Cells (AD-SVFs) and Human Adipose-Derived Mesenchymal Stem Cells (AD-MSCs): Enzymatic Digestion Versus Mechanical Centrifugation

Autologous therapies using adipose-derived stromal vascular fraction (AD-SVFs) and adult adipose-derived mesenchymal stem cells (AD-MSCs) warrant careful preparation of the harvested adipose tissue. Currently, no standardized technique for this preparation exists. Processing quantitative standards (PQSs) define manufacturing quantitative variables (such as time, volume, and pressure). Processing qualitative standards (PQLSs) define the quality of the materials and methods in manufacturing. The purpose of the review was to use PQSs and PQLSs to report the in vivo and in vitro results obtained by different processing kits that use different procedures (enzymatic vs. non-enzymatic) to isolate human AD-SVFs/AD-MSCs. PQSs included the volume of fat tissue harvested and reagents used, the time/gravity of centrifugation, and the time, temperature, and tilt level/speed of incubation and/or centrifugation. PQLSs included the use of a collagenase, a processing time of 30 min, kit weight, transparency of the kit components, the maintenance of a closed sterile processing environment, and the use of a small centrifuge and incubating rocker. Using a kit with the PQSs and PQLSs described in this study enables the isolation of AD-MSCs that meet the consensus quality criteria. As the discovery of new critical quality attributes (CQAs) of AD-MSCs evolve with respect to purity and potency, adjustments to these benchmark PQSs and PQLs will hopefully isolate AD-MSCs of various CQAs with greater reproducibility, quality, and safety. Confirmatory studies will no doubt need to be completed.

Effect of platelet-rich plasma on peri-implant trabecular bone volume and architecture: A preclinical micro-CT study in beagle dogs

OBJECTIVES

To evaluate the peri-implant trabecular bone volume and architecture changes with 6-month follow-up after local application of platelet-rich plasma (PRP) and platelet-poor plasma (PPP) using high-resolution micro-CT.

MATERIAL AND METHODS

Seventy-two dental implants were placed into healed mandibular sites of 9 beagle dogs. Implants were randomly divided into 4 groups following a split-mouth design: control I; control II; PPP; and PRP. Primary and secondary stabilities were assessed using resonance frequency analyses. At 1, 3, and 6 months after implant loading, trabecular structural parameters were evaluated at 0.5, 1, and 1.5 mm away from implants using micro-CT (voxel = 20 μm).

RESULTS

Primary and secondary stabilities were equivalent in all conditions. PPP and PRP groups showed higher bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) but lower trabecular separation (Tb.Sp) and total porosity percentage (Po (tot)) at all 3 time points. A significant decrease in BV/TV and Tb.Th was found for the control groups after 3 months of healing, while this was not observed in both the PPP and PRP groups. However, no distinct difference was found between the PRP and PPP groups over time. Moreover, as the investigated distance from the implant surface increased, BV/TV and Po (tot) within the same group and time point stayed the same, yet Tb.Th and Tb.Sp continued to increase.

CONCLUSIONS

Platelet-rich plasma and PPP with conventional implant placement lead to similar primary and secondary implant stability, but improved peri-implant bone volume and structural integration. The present research does not seem to suggest a different bone remodeling pattern when using PRP or PPP.

Platelet-Rich Plasma: Principles and Applications in Plastic Surgery

Platelet-rich plasma (PRP) is an autogenously harvested liquid platelet concentrate extracted from a patient's peripheral blood that contains higher than baseline concentrations of growth factors and cytokines. This innovative new technology has demonstrated great promise in the field of plastic surgery, and its use has been evaluated in several clinical settings including wound healing, hair restoration, and skin rejuvenation. The goal of this article is to explain the biology behind PRP and to review the basic principles involved in its preparation. This will be followed by a discussion of some clinical applications of PRP in both aesthetic and reconstructive plastic surgery.

Effects of single- and double-layered resorbable membranes and platelet-rich fibrin on bone healing

OBJECTIVES

Research has been ongoing on achieving optimum bone healing in the reconstruction of bone loss. Clinically, soft tissue migration into the already existing bone defects is the leading cause of unfavourable bone healing. Platelet-rich fibrin, a recent material that is used to promote bone healing, was compared with single- and double-layered resorbable collagen membranes to determine whether a healing protocol which increases patient comfort is possible.

MATERIALS AND METHODS

Sixty adult female Sprague-Dawley rats were used. The rats were divided into five main groups as a sacrification group, a control group, and three experimental groups. The bone defects experimental group 1 were covered with a single-layer collagen membrane, and experimental group 2 were covered with the double-layered collagen membrane. Defects on the experimental group 3 were covered with platelet-rich fibrin membranes which were derived from the sacrification group. The animals in the main groups were also divided into eight subgroups arranged by sacrification periods on day 7 and day 28.

RESULTS

Statistical analysis of our study revealed that new bone formation in experimental group 3 was significantly higher than in other groups. Fibrosis was found to be lower in experimental group 3 than in any other group. No significant differences were found between experimental group 1 and the control group.

CONCLUSION

Platelet-rich fibrin, which can be used as an autologous membrane which promotes bone healing, yields better clinical result compared to collagen membranes.

CLINICAL RELEVANCE

Histopathologic evaluation has been carried out regarding the effect of platelet-rich fibrin and collagen membranes applied on bone recovery. Our objective is to contribute to barrier membrane studies that continue to guide and accelerate bone recovery.

Is the combination of fat grafts and platelet rich plasma effective in rats?

PURPOSE:

To investigate if the association of fat grafts and platelet-rich plasma (PRP) improves graft viability in female rats.

METHODS:

This is an experimental, randomized and blinded study, which involved 47 rats. Fat was harvested from the inguinal region and grafted to the cranial region. The experimental group consisted of PRP-enriched fat grafts (n=22) whilst the control group consisted of fat graft only (n=25). After a 100-day period, the animals were euthanised and the fat grafts were analyzed using scores from 0 (absent) to 4 (abundant), in optical microscopy by two independent and blinded pathologists.

RESULTS:

Regarding fat graft cell viability, the PRP group scored moderate/abundant in 63% of cases and the fat graft only group scored absent/slight in 72% of cases (p=0.03). The PRP group also presented lower fat necrosis scores when compared to the fat graft only group (p=0.03). Tumors (dermoid cysts) within the fat grafts were observed in three animals in which the grafts were mixed with PRP.

CONCLUSION:

Platelet-rich plasma improves the viability and integration of fat grafts in rats, but more studies are needed to fully understand the exact mechanisms that lead to this improvement and assess the safety of the method for use in humans.

Platelet-rich plasma for regeneration of neural feedback pathways around dental implants: a concise review and outlook on future possibilities

Along with the development of new materials, advanced medical imaging and surgical techniques, osseointegrated dental implants are considered a successful and constantly evolving treatment modality for the replacement of missing teeth in patients with complete or partial edentulism. The importance of restoring the peripheral neural feedback pathway and thus repairing the lack of periodontal mechanoreceptors after tooth extraction has been highlighted in the literature. Nevertheless, regenerating the nerve fibers and reconstructing the neural feedback pathways around osseointegrated implants remain a challenge. Recent studies have provided evidence that platelet-rich plasma (PRP) therapy is a promising treatment for musculoskeletal injuries. Because of its high biological safety, convenience and usability, PRP therapy has gradually gained popularity in the clinical field. Although much remains to be learned, the growth factors from PRP might play key roles in peripheral nerve repair mechanisms. This review presents known growth factors contributing to the biological efficacy of PRP and illustrates basic and (pre-)clinical evidence regarding the use of PRP and its relevant products in peripheral nerve regeneration. In addition, the potential of local application of PRP for structural and functional recovery of injured peripheral nerves around dental implants is discussed.

Platelet preparations in dentistry: How? Why? Where? When?

The aim of this article is to review the outcomes of platelet preparations in dentistry. A structured electronic search discovered 348 articles, which described the use of autologous platelet concentrates with a relevance to clinical dentistry. Among these articles, 220 articles investigated platelet rich plasma, 99 investigated platelet rich fibrin, 22 investigated plasma rich in growth factors and 7 investigated the use of concentrated growth factors. Several studies reported beneficial treament outcomes in terms of enhanced bone and soft tissue regeneration.

Platelet-rich preparations to improve healing. Part II: platelet activation and enrichment, leukocyte inclusion, and other selection criteria

Multiple platelet-rich preparations have been reported to improve wound and bone healing, such as platelet-rich plasma (PRP) and platelet rich fibrin (PRF). The different methods employed during their preparation are important, as they influence the quality of the product applied to a wound or surgical site. Besides the general protocol for preparing the platelet-rich product (discussed in Part 1 of this review), multiple choices need to be considered during its preparation. For example, activation of the platelets is required for the release and enmeshment of growth factors, but the method of activation may influence the resulting matrix, growth factor availability, and healing. Additionally, some methods enrich leukocytes as well as platelets, but others are designed to be leukocyte-poor. Leukocytes have many important roles in healing and their inclusion in PRP results in increased platelet concentrations. Platelet and growth factor enrichment reported for the different types of platelet-rich preparations are also compared. Generally, TGF-β1 and PDGF levels were higher in preparations that contain leukocytes compared to leukocyte-poor PRP. However, platelet concentration may be the most reliable criterion for comparing different preparations. These and other criteria are described to help guide dental and medical professionals, in large and small practices, in selecting the best procedures for their patients. The healing benefits of platelet-rich preparations along with the low risk and availability of simple preparation procedures should encourage more clinicians to incorporate platelet-rich products in their practice to accelerate healing, reduce adverse events, and improve patient outcomes.

Activated platelets rescue apoptotic cells via paracrine activation of EGFR and DNA-dependent protein kinase

Platelet activation is a frontline response to injury, not only essential for clot formation but also important for tissue repair. Indeed, the reparative influence of platelets has long been exploited therapeutically where application of platelet concentrates expedites wound recovery. Despite this, the mechanisms of platelet-triggered cytoprotection are poorly understood. Here, we show that activated platelets accumulate in the brain to exceptionally high levels following injury and release factors that potently protect neurons from apoptosis. Kinomic microarray and subsequent kinase inhibitor studies showed that platelet-based neuroprotection relies upon paracrine activation of the epidermal growth factor receptor (EGFR) and downstream DNA-dependent protein kinase (DNA-PK). This same anti-apoptotic cascade stimulated by activated platelets also provided chemo-resistance to several cancer cell types. Surprisingly, deep proteomic profiling of the platelet releasate failed to identify any known EGFR ligand, indicating that activated platelets release an atypical activator of the EGFR. This study is the first to formally associate platelet activation to EGFR/DNA-PK – an endogenous cytoprotective cascade.

Relevant aspects of centrifugation step in the preparation of platelet-rich plasma

Introduction. Platelet-Rich Plasma (PRP) is rich in growth factors, playing important role in tissue healing. The wide variation of reported protocols for preparation of PRP leads to variable compositions, which induce different biological responses and prevent results comparison. This study aims to highlight relevant aspects of the centrifugation step to obtain reproducible results and overall quality. Material and Methods. Samples of blood were collected from 20 healthy donors that have signed free informed consent. Two centrifugation steps (spins) were analyzed for the influence of centrifugal acceleration, time, processed volume, and platelet gradient. The Pure Platelet-Rich Plasma (P-PRP) was characterized as platelet concentration, integrity, and viability (sP-selectin measurement). Results. Lower centrifugal accelerations favour platelet separation. The processing of 3.5 mL of blood at 100 ×g for 10 min (1st spin), 400 ×g for 10 min (2nd spin), withdrawing 2/3 of remnant plasma, promoted high platelet recovery (70–80%) and concentration (5x) maintaining platelet integrity and viability. The recovery of platelets was reduced for a larger WB volume (8.5 mL) processed. Conclusion. Centrifugal acceleration, time, WB processed volume, and minimization of the platelet gradient before sampling are relevant aspects to ensure reproducible compositions within the autologous nature of PRP.

Bone regeneration with plasma-rich-protein following enucleation of traumatic bone cyst

Traumatic bone cyst is an uncommon non-epithelium lined cavity and is seen frequently in young individuals. The lesion occurs more commonly in the mandible, involving the posterior region. It is generally asymptomatic and is diagnosed on routine radiographic examination. The cystic cavity is usually empty and there is scanty material for histological examination. Surgical curettage is usually done and recurrence is rare. A case of traumatic bone cyst occurring in the anterior region of mandible in a young boy is presented. Following surgical intervention, plasma-rich-protein was placed in the cystic cavity. The lesion showed progressive resolution and bone regeneration of the cystic cavity within a short period of time.

Platelet-rich plasma (PRP) in dental and oral surgery: from the wound healing to bone regeneration

Platelet-rich plasma (PRP) is a new approach to tissue regeneration and it is becoming a valuable adjunct to promote healing in many procedures in dental and oral surgery, especially in aging patients. PRP derives from the centrifugation of the patient's own blood and it contains growth factors that influence wound healing, thereby playing an important role in tissue repairing mechanisms. The use of PRP in surgical practice could have beneficial outcomes, reducing bleeding and enhancing soft tissue healing and bone regeneration. Studies conducted on humans have yielded promising results regarding the application of PRP to many dental and oral surgical procedures (i.e. tooth extractions, periodontal surgery, implant surgery). The use of PRP has also been proposed in the management of bisphosphonate-related osteonecrosis of the jaw (BRONJ) with the aim of enhancing wound healing and bone maturation. The aims of this narrative review are: i) to describe the different uses of PRP in dental surgery (tooth extractions and periodontal surgery) and oral surgery (soft tissues and bone tissue surgery, implant surgery and BRONJ surgery); and ii) to discuss its efficacy, efficiency and risk/benefit ratio. This review suggests that the use of PRP in the alveolar socket after tooth extractions is certainly capable of improving soft tissue healing and positively influencing bone regeneration but the latter effect seems to decrease a few days after the extraction. PRP has produced better results in periodontal therapy in association with other materials than when it is used alone. Promising results have also been obtained in implant surgery, when PRP was used in isolation as a coating material. The combination of necrotic bone curettage and PRP application seem to be encouraging for the treatment of refractory BRONJ, as it has proven successful outcomes with minimal invasivity. Since PRP is free from potential risks for patients, not difficult to obtain and use, it can be employed as a valid adjunct in many procedures in oral and dental surgery. However, further RCTs are required to support this evidence.

The use of platelet-rich plasma in plastic surgery: a systematic review

OBJECTIVE

The study's aim was to evaluate the available evidence regarding the use of platelet-rich plasma in plastic and reconstructive surgery, through implementation of a systematic review of the literature.

DATA SOURCES

PubMed and The Cochrane Library were searched using MeSH terms: 'platelet rich plasma' and 'plastic surgery' for all publications up to July 2011. All English, German, French and Dutch papers were included. In addition, the reference lists of relevant articles were searched for potentially appropriate publications.

STUDY SELECTION

Included studies needed to report on topics related to plastic and reconstructive surgery, mentioning at least one clinical end point. Both in vivo and in vitro comparative studies, performed in humans or animals, were included. A total of 82 publications were found, of which 40 studies met the inclusion criteria and were relevant to be used in this systematic review.

DATA EXTRACTION

Data from retrieved studies were reviewed and tabulated according to year of publication, study design, human or animal studies, characteristics of the population, mode of application, outcomes and preparation method.

DATA SYNTHESIS

A total of 15 randomised controlled trials and 25 case-control studies were found. Thirty-six publications demonstrated favourable outcomes with the use of platelet-rich plasma. The included articles were divided into three topics related to plastic surgery: wound healing, fat grafting and bone grafting.

CONCLUSIONS

This systematic review describes a substantially beneficial effect of platelet-rich plasma for several indications, including a better wound healing rate, an increased survival rate of fat grafts and an enhancement of bone graft regeneration.

Effect of autologous platelet-rich plasma on bone regeneration in mandibular fractures

OBJECTIVES

The aim of this study was to assess the effect of autologous platelet-rich plasma (PRP) on bone regeneration in mandibular fractures via a cone beam computed tomography (CBCT).

PATIENTS AND METHODS

Twenty-four patients having parasymphyseal fractures participated in this study. They were randomly divided into two equal groups. Group A was treated by two titanium miniplates and screws plus local application of activated PRP along the fracture line, whereas group B was treated by the same bone plates and screws without application of PRP. The patients were recalled at 1 week, 3 and 6 months after surgery for clinical assessment and measuring the bone density via CBCT at a region of interest (ROI) including the fracture line.

RESULTS

The mean values of the bone density measurements, in both groups, were higher at 3 and 6 months than 1 week after surgery. At 1 week after surgery, the values were 542 ± 93 HU and 515 ± 81 HU in group A and B, respectively. In group A, the mean value of bone density measurements was 728 ± 58 HU (range 620-796 HU) at 3 months after surgery and it was 1024 ± 188 HU (range 825-1490 HU) 6 months later. While in group B, the mean values of the bone density measurements at the ROI were 600 ± 78 HU (range 520-790 HU) and 756 ± 53 HU (range 710-890 HU) at 3 and 6 months after surgery, respectively. The increase in the bone density measurements at 3 and 6 months after surgery was statistically significant only in group A (P = 0.0002 and P = 0.0001, respectively).

CONCLUSIONS

It can be concluded that direct application of the PRP along the fracture lines may enhance the bone regeneration in mandibular fractures.

Platelet-rich plasma and blood components for non-transfusion use: technical and medicolegal aspects

There are a large number of publications describing the use of platelet-rich plasma (PRP) in multiple fields of application. These illustrate a large number of therapeutic elements with different and specific actions within 'platelet gel' (this term is used in the current regulations to define this product). This term, however, lacks specificity and, depending on the method used in its production is variable both in its blood composition and in platelet concentration, and several publications consider better and easier methods of platelet gel production, which may or may not lead to greater standardization in the product. The authors illustrate the general aspects of PRP and other blood components for non-transfusion use, briefly touching on the history and different fields of application and the rational of for its use. Given the increased use of such preparations, the authors describe critically the regulations in force in Europe and propose a new regulatory framework aimed to simplify and facilitate the use of such material as a therapeutic agent within medicine.

Platelet gel: applications in dental regenerative surgery

BACKGROUND

Platelet growth factors obtained from platelet-rich plasma (PRP) are used in prosthetic and periodontal regenerative therapy in dentistry. Increased microvascular proliferation in the first 20 days is followed by enhanced osteoblast activity and immature osteoid formation within 3-6 weeks, improving the quality and quantity of newly formed bone tissue. The aim of this study was to evaluate, through three-dimensional X-ray monitoring, the amount of bone obtained after bone regeneration treatment with platelet gel from autologous PRP.

MATERIALS AND METHODS

Patients eligible for regenerative treatment of atrophic alveolar bone of the maxilla or mandible were studied. The patients' autologous whole blood was collected at the Department of Immunology and Transfusion of San Matteo Hospital for the preparation of platelet gel. The bone at the treated sites was analysed prior to and 4 months after the treatment using the three-dimensional X-ray system Galileos.

RESULTS

Over a period of 6 years, 133 patients were treated: 304 implants were inserted and there were five cases of failure. The regenerated bone area consisted of histologically immature osteoid tissue composed of thin trabeculae of vital bone and nuclei of osteocytes, associated with fibro-connective tissue.

DISCUSSION

This co-operative trial between the Transfusion Centre, for standardised production and validation of the platelet gel, and the Dental Surgery room for its application showed that the technique appears effective and safe. Although difficulties were encountered because of the small sample size and the inability to carry out long-term histological controls, the use of small amounts of PRP (5-10%) combined with autologous bone (15-20%) and alloplastic material appears to reduce the need for bone grafting.