Angiogenic properties of sustained release platelet-rich plasma: characterization in-vitro and in the ischemic hind limb of the mouse

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Enhanced Diabetic Rat Wound Healing by Platelet-Rich Plasma Adhesion Zwitterionic Hydrogel

BACKGROUND

The skin is the largest organ in the human body and serves as a barrier for protective, immune, and sensory functions. Continuous and permanent exposure to the external environment results in different levels of skin and extracellular matrix damage. During skin wound healing, the use of good dressings and addition of growth factors to the wound site can effectively modulate the rate of wound healing. A dressing containing bioactive substances can absorb wound exudates and reduce adhesion between the wound and dressing, whereas growth factors, cytokines, and signaling factors can promote cell motility and proliferation.

AIM AND OBJECTIVES

We prepared a functional wound dressing by combining platelet-rich plasma (PRP) and zwitterionic hydrogels. Functional wound dressings are rich in various naturally occurring growth factors that can effectively promote the healing process in various types of tissues and absorb wound exudates to reduce adhesion between wounds and dressings. Furthermore, PRP-incorporated zwitterionic hydrogels have been used to repair full-thickness wounds in Sprague-Dawley rats with diabetes (DM SD).

MATERIALS AND METHODS

Fibroblasts and keratinocytes were cultured with PRP, zwitterionic hydrogels, and PRP-incorporated zwitterionic hydrogels to assess cell proliferation and specific gene expression. Furthermore, PRP-incorporated zwitterionic hydrogels were used to repair full-thickness skin defects in DM SD rats.

RESULTS

The swelling ratio of hydrogel, hydrogel + PRP1000 (108 platelets/mL), and hydrogel + PRP1000 (109 platelets/mL) groups were similar (~07.71% ± 1.396%, 700.17% ± 1.901%, 687.48% ± 4.661%, respectively) at 144 hours. The tensile strength and Young modulus of the hydrogel and hydrogel + PRP10000 groups were not significantly different. High concentrations of PRP (approximately 108 and 109 platelets/mL) effectively promoted the proliferation of fibroblasts and keratinocytes. The zwitterionic hydrogels were not cytotoxic to any cell type. High PRP concentration-incorporated zwitterionic hydrogels increased the rate of cell proliferation and significantly increased the expression of characteristic genes such as collagen, fibronectin, involucrin, and keratin. Subsequently, zwitterionic hydrogels with high PRP concentrations were used to repair full-thickness skin defects in DM SD rats, and a wound healing rate of more than 90% was recorded on day 12.

CONCLUSIONS

PRP contains high concentrations of growth factors that promote cell viability, enhance specific gene expression, and have a high medical value in cell therapy. Zwitterionic hydrogels have a 3-dimensional interconnected microporous structure and can resist cell adhesion without causing cytotoxicity. Platelet-rich plasma-incorporated zwitterionic hydrogels further enhance the cellular properties and provide an effective therapeutic option for wound healing.

The impact of zinc on the molecular signaling pathways in the diabetes disease

Since there's been an upsurge in people with diabetes or pre-diabetes conditions, many studies have been conducted to evaluate approaches for reducing the complications of diabetes. One of the most common therapeutic elements suggested for this purpose is zinc (Zn). Zn has long been shown to positively improve complications of both type 1 and type 2 diabetes. This review aims to provide comprehensive information about the influence of Zn on the various signaling pathways in multiple tissues with diabetic conditions, with great attention to the treatment period and effective dose of Zn.

The effect of allogenic freeze-dried platelet-rich plasma in increasing the number of fibroblasts and neovascularization in wound healing

Background

Material and methods

Results

Conclusions

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There were significant differences in the average number of fibroblasts in the control groups and the treatment groups.

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There were major differences in the average amount of neovascularization between the control group and the treatment group.

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Allogenic freeze-dried PRP could increase the number of fibroblasts and neovascularization in wound healing.

Regenerative effect of platelet-rich plasma in the murine ischemic limbs

AIMS

The purpose of this study was to investigate the effect of PPRP (pure PRP) and LPRP (PRP with leukocytes) on recovery from limb ischemia and on expression of growth factors involved in angiogenesis, myogenesis and fibrogenesis.

MATERIAL AND METHODS

PPRP and LPRP prepared by centrifugation were added to cultures of C2C12 and NIH3T3 cells (1 or 10% PRPs) to evaluate alterations in cell metabolism and expression of growth factors by MTT, ELISA and RT-qPCR, respectively. To evaluate in vivo regenerative effects, PRPs were injected into the ischemic limbs of BALB/c mice and muscle mass/strength and histomorphometry were evaluated after 30 days.

KEY FINDINGS

Mice treated with PRPs after limb ischemia showed an increase in the size of myofibers and muscle strength, reduced fibrosis and adipocytes, and decreased capillary density and necrosis scores compared to untreated mice. In cell culture, serum deprivation reduced the viability of C2C12 and NIH3T3 cells to about 50%, but the addition of 1% PRPs completely recovered this loss. Both PRPs, downregulated most of the tested genes; however, angiogenic gene Vegfa in C2C12 and the fibrogenic genes Col1a1 and Col3a1 in NIH3T3 cells were upregulated by LPRP.

SIGNIFICANCE

PPRP and LPRP had similar effects in regulation of genes involved in angiogenesis, myogenesis and fibrogenesis. However, the presence of leucocytes did not significantly affect regenerative activities of PRP in the ischemic limb.

Healing through the lens of immunothrombosis: Biology-inspired, evolution-tailored, and human-engineered biomimetic therapies

Evolution, from invertebrates to mammals, has yielded and shaped immunoclotting as a defense and repair response against trauma and infection. This mosaic of immediate and local wound-sealing and pathogen-killing mechanisms results in survival, restoration of homeostasis, and tissue repair. In mammals, immunoclotting has been complemented with the neuroendocrine system, platelets, and contact system among other embellishments, adding layers of complexity through interconnecting blood-born proteolytic cascades, blood cells, and the neuroendocrine system. In doing so, immunothrombosis endows humans with survival advantages, but entails vulnerabilities in the current unprecedented and increasingly challenging environment. Immunothrombosis and tissue repair appear to go hand in hand with common mechanisms mediating both processes, a fact that is underlined by recent advances that are deciphering the mechanisms of the repair process and of the biochemical pathways that underpins coagulation, hemostasis and thrombosis. This review is intended to frame both the universal aspects of tissue repair and the therapeutic use of autologous fibrin matrix as a biology-as-a-drug approach in the context of the evolutionary changes in coagulation and hemostasis. In addition, we will try to shed some light on the molecular mechanisms underlying the use of the autologous fibrin matrix as a biology-inspired, evolution-tailored, and human-engineered biomimetic therapy.

Closure of a Difficult-to-Manage Chronic Pressure Injury with the Use of Autologous Platelet-Rich Plasma (APRP)

Pressure injury (PI) corresponds to a skin damage of ischemic aetiology that affects the integrity of the skin and is produced by prolonged pressure or friction between a hard internal and external surface. Treatment can be challenging when there is no resolution with usual care. The use of autologous platelet-rich plasma (APRP) gel arises as a therapeutic possibility in the presence of chronic pressure injuries. The case of a patient with chronic PI who has been treated with APRP is presented, achieving resolution of the lesion.

Platelet-Derived Biomaterials Inhibit Nicotine-Induced Intervertebral Disc Degeneration Through Regulating IGF-1/AKT/IRS-1 Signaling Axis

Apart from aging process, adult intervertebral disc (IVD) undergoes various degenerative processes. However, the nicotine has not been well identified as a contributing etiology. According to a few studies, nicotine ingestion through smoking, air or clothing may significantly accumulate in active as well as passive smokers. Since nicotine has been demonstrated to adversely impact various physiological processes, such as sympathetic nervous system, leading to impaired vasculature and cellular apoptosis, we aimed to investigate whether nicotine could induce IVD degeneration. In particular, we evaluated dose-dependent impact of nicotine in vitro to simulate its chronic accumulation, which was later treated by platelet-derived biomaterials (PDB). Further, during in vivo studies, mice were subcutaneously administered with nicotine to examine IVD-associated pathologic changes. The results revealed that nicotine could significantly reduce chondrocytes and chondrogenic indicators (Sox, Col II and aggrecan). Mice with nicotine treatment also exhibited malformed IVD structure with decreased Col II as well as proteoglycans, which was significantly increased after PDB administration for 4 weeks. Mechanistically, PDB significantly restored the levels of IGF-1 signaling proteins, particularly pIGF-1 R, pAKT, and IRS-1, modulating ECM synthesis by chondrocytes. Conclusively, the PDB impart reparative and tissue regenerative processes by inhibiting nicotine-initiated IVD degeneration, through regulating IGF-1/AKT/IRS-1 signaling axis.

The C5a/C5a receptor 1 axis controls tissue neovascularization through CXCL4 release from platelets

Platelets contribute to the regulation of tissue neovascularization, although the specific factors underlying this function are unknown. Here, we identified the complement anaphylatoxin C5a-mediated activation of C5a receptor 1 (C5aR1) on platelets as a negative regulatory mechanism of vessel formation. We showed that platelets expressing C5aR1 exert an inhibitory effect on endothelial cell functions such as migration and 2D and 3D tube formation. Growth factor- and hypoxia-driven vascularization was markedly increased in C5ar1^-/- mice. Platelet-specific deletion of C5aR1 resulted in a proangiogenic phenotype with increased collateralization, capillarization and improved pericyte coverage. Mechanistically, we found that C5a induced preferential release of CXC chemokine ligand 4 (CXCL4, PF4) from platelets as an important antiangiogenic paracrine effector molecule. Interfering with the C5aR1-CXCL4 axis reversed the antiangiogenic effect of platelets both in vitro and in vivo.In conclusion, we identified a mechanism for the control of tissue neovascularization through C5a/C5aR1 axis activation in platelets and subsequent induction of the antiangiogenic factor CXCL4.

Resumed ovarian function and pregnancy in early menopausal women by whole dimension subcortical ovarian administration of platelet-rich plasma and gonadotropins

OBJECTIVE

This study was designed to investigate if whole dimension subcortical ovarian administration of platelet-rich plasma with gonadotropin, in proximity to most ovarian follicles, is effective in restoring ovarian functions in women during early menopause.

METHODS

Platelet-rich plasma, prepared from 40 mL of autologous peripheral blood using the buffy coat method, was injected into extended subcortical area of bilateral ovaries along with recombinant follicle-stimulating hormone (rFSH) (Gonal-F 300IU) under laparoscopic guidance. The posttreatment ovarian folliculogenesis and serum levels of FSH, luteinizing hormone (LH), and estradiol were followed up for 6 months at weekly to monthly intervals. IVF was carried out in women resuming ovulatory functions.

RESULTS

Twelve early menopausal women with mean age of 44.42 ± 2.84 were enrolled. After treatment, 11 women resumed their menstrual period in 37.1 ± 23.5 days. Their average serum FSH was 70.47 ± 20.92 and 26.22 ± 17.55 IU/L, luteinizing hormone was 34.81 ± 11.86 and 14.3 ± 12.8 IU/L, before and after treatment, respectively. The mid-cycle E2 was 251.1 ± 143.8 pg/mL. Ten oocyte retrievals were carried out among six participants, four of them received controlled ovarian stimulation and another two using natural ovulation cycles. Thirteen mature eggs were retrieved which were then ICSI fertilized to obtain 10 normally fertilized 2PN oocytes. Two participants had cleavage stage embryos transferred of which one achieved clinical pregnancy.

CONCLUSIONS

Whole dimension subcortical ovarian administration of platelet-rich plasma with gonadotropin was shown to restore ovarian functions, at least temporarily, and could increase the probability of pregnancy using autologous oocytes in women with early menopause.

Comparison of the Effects of Repeated Applications of Platelet-Rich Plasma versus Platelet-Poor Plasma on Fat Graft Survival in Nude Mice

Autologous fat grafting has been widely used for soft tissue filling in plastic surgery. Platelet-rich plasma (PRP) could play a wide role in health and disease because of containing a variety of growth factors and cytokines. Although previous studies have described the positive effect of autologous PRP mixed with fat grafts, only minimal improvements in fat graft survival have been reported. The present study is aimed at comparing the effects of PRP and platelet-poor plasma (PPP) on the survival and quality of fat grafting. We built a 180-day nude mouse model implanted with a fat graft supplemented with PRP, PPP, or saline, respectively. The above reagents (PRP, PPP, or saline) were injected two additional times after the initial engraftment. The survival ratio of the fat grafts and the capillary density in the PRP group were significantly higher than those in the PPP group and the saline group (control group) at 15, 30, 90, and 180 days posttransplantation (P < 0.05). The survival ratio of the PPP group was higher than that of the saline group (P < 0.05), but the capillary density in the PPP group was not significantly different from that in the saline group at any time point (P > 0.05). We hence conclude that the repeated application of PRP or PPP three times can enhance the survival of fat grafts within 180 days. Moreover, the effect of PRP is superior to that of PPP.

Wound dressings as growth factor delivery platforms for chronic wound healing

Introduction: Years of tissue engineering research have clearly demonstrated the potential of integrating growth factors (GFs) into scaffolds for tissue regeneration, a concept that has recently been applied to wound dressings. The old concept of wound dressings that only take a passive role in wound healing has now been overtaken, and advanced dressings which can take an active part in wound healing, are of current research interest.Areas covered: In this review we will focus on the recent strategies for the delivery of GFs to wound sites with an emphasis on the different approaches used to achieve fine tuning of spatial and temporal concentrations to achieve therapeutic efficacy.Expert opinion: The use of GFs to accelerate wound healing and reduce scar formation is now considered a feasible therapeutic approach in patients with a high risk of infections and complications. The integration of micro - and nanotechnologies into wound dressings could be the key to overcome the inherent instability of GFs and offer adequate control over the release rate. Many investigations have led to encouraging outcomes in various in vitro and in vivo wound models, and it is expected that some of these technologies will satisfy clinical needs and will enter commercialization.

Effect of Cord Blood Platelet Gel on wound healing capacity of human Mesenchymal Stromal Cells

BACKGROUND

Wound healing is a dynamic process, involving the recruitment of growth factors, cytokines, chemokines and cellular populations. Recently, the Cord Blood Platelet Gel (CBPG) has been applied successfully in wound closure and tissue regeneration. Moreover, its proper combination with stem cell populations such as Mesenchymal Stromal Cells (MSCs) may positively improve the wound healing process. Based on the above data, this study aimed to the evaluation of wound healing capacity of MSCs combined with CBPG under in vitro conditions.

METHODS

Initially, CBPG was developed from Cord Blood Units (CBUs). The determination of wound healing ability of MSCs was performed using the scratch wound assay. In addition, the morphological features, immunophenotypical characteristics and differentiation capacity of MSCs were evaluated.

RESULTS

Scratch wound assay results showed, that CBPG could positively stimulate the MSCs migration. Moreover, MSCs cultured in presence of CBPG were characterized by elongated shape and improved stemness properties as it was indicated by flow cytometric analysis and differentiation process.

CONCLUSION

These results clearly showed the beneficial effect of CBPG in combination with MSCs in wound healing. The proper combination of CBPG with stem cells strategy may enhance the healing process in patients with skin erosions.

Sustained release of human platelet lysate growth factors by thermosensitive hydroxybutyl chitosan hydrogel promotes skin wound healing in rats

This study evaluated the effect of thermosensitive hydroxybutyl chitosan (HBC) hydrogel loaded with human platelet lysate (hPL) on skin wound healing in rats. hPLs were generated by freeze-thaw method of platelet-rich plasma from healthy donors. Successful grafting of hydroxybutyl group to chitosan molecular chain to obtain HBC hydrogel was confirmed by Fourier-transform infrared spectroscopy. HBC/hPL was prepared by combining 10% (vol/vol) hPL with HBC solution. Surface morphologies were determined by Scanning Electron Microscopy, rheological properties were measured by rheometer, and sustained release of factors from HBC/hPL was measured by enzyme-linked immunoassay. We evaluated the in vitro effect of HBC/hPL on human umbilical cord vein endothelial cell (HUVEC) proliferation, migration, and tube formation. The effect of growth factors released from HBC/hPL in promoting skin wound healing was evaluated by gross observation, histology, immunohistochemistry, and immunofluorescence in vivo. Rheological analyses indicated the gelation temperatures of HBC and HBC/hPL were 17 and 14°C, respectively. ELISA showed sustained release of human platelet-derived growth factor, basic fibroblast growth factor, and transforming growth factor-β1 from HBC/hPL hydrogel. In vitro studies revealed HBC/hPL promoted greater levels of HUVECs proliferation, migration, and tube formation than the HBC and control groups. In vivo studies showed better wound healing, greater amounts of newly formed collagen, as well as neovascular and neo-epidermis markers in the wound site of HBC/hPL-treated group compared to the HBC and control groups. HBC/hPL is a promising potential therapeutic agent for promoting skin wound healing via the sustained release of growth factors.

Effect of autologous transplant of peripheral blood mononuclear cells in combination with proangiogenic factors during experimental revascularization of lower limb ischemia

Peripheral blood mononuclear cells (PBMCs) contain a cell fraction of mononuclear progenitor cells (MPCs), which own significant angiogenic potential. Autologous transplant of PBMC and/or platelet-rich plasma (PRP) promotes endothelial cells differentiation in experimental lower limb ischemia, which is considered a safe and effective strategy to support revascularization, either in animal models or clinical trials. In addition, thrombin has been proposed to enrich biological scaffolds, hence increasing MPC viability after intramuscular administration, whereas proangiogenic mediators such as vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNF-α), inhibitor of the plasminogen activator-1 (PAI-1), and chemokine (CXCL1; GRO-α) participate in the endothelial response to ischemia, through their proangiogenic effects over endothelial cells proliferation, survival, migration, endothelial integrity maintenance, and physiologic vascular response to injury. In the present study, we describe the effect of autologous PBMCs transplant and PRP, either with or without thrombin, over proangiogenic mediators (measured by enzyme-linked immunosorbent assay) and revascularization response (angiographic vascular pattern at 30 days after vascular occlusion) in a rat model of lower limb ischemia. The group treated with PBMC + PRP significantly induced PAI-1, an effect that was prevented by the addition of thrombin. Furthermore, treatment with PBMC + PRP + thrombin resulted in the induction of VEGF. GRO-α showed a sensitive induction of all proangiogenic mediators. All treatments significantly stimulated revascularization, according to angiographic assessment, whereas higher effect was observed with PBMC + PRP treatment (p < .0001). In conclusion, autologous PBMC transplant stimulates revascularization during experimental ischemia of the lower limb, whereas particular effects over proangiogenic and fibrinolytic mediators may be attributed to PBMCs and its combination with PRP and thrombin.

The protective effect of platelet-rich plasma administrated on ovarian function in female rats with Cy-induced ovarian damage

PURPOSE

We evaluated the protective effect of PRP on ovarian function in female rats with cyclophosphamide (Cy)-induced ovarian damage.

METHODS

Thirty-two adult female Sprague-Dawley rats were randomly divided into four groups. Group 1 (control-sodium chloride 0.9%; 1 mL/kg, single-dose ip injection), group 2 (Cy); 75 mg/kg, single-dose ip injection and sodium chloride 0.9% (1 mL/kg, single-dose ip injection), group 3 Cy plus PRP, Cy (75 mg/kg, single-dose and PRP (200 μl, single-dose) ip injection), group 4 (PRP, 200 μl, single-dose ip injection). Primordial, antral, and atretic follicle counts; serum anti-Müllerian hormone (AMH) levels; AMH-positive granulosa cells; and gene expression analysis of Ddx4 were assessed.

RESULTS

Serum AMH levels were significantly lower in group 2 compared to groups 1, 3, and 4 (p < 0.01, p < 0.01, and p = 0.04, respectively). A significant difference was found in the primordial, primary, secondary, antral, and atretic follicle counts between all groups (p < 0.01). There was a statistically significant difference in AMH-positive staining primary, secondary, and antral follicles count between the groups (p < 0.01). There was a statistically significant difference in primary, secondary, and antral AMH positive staining follicle intensity score between the groups (p < 0.01). Ddx4 expression in group 4 was highest compared to other groups.

CONCLUSION

Our study may provide evidence that PRP could protect ovarian function against ovarian damage induced by Cy. It could lead to improved primordial, primary, secondary, and antral follicle numbers.

Evaluation of platelet-rich plasma from diabetic donors shows increased platelet vascular endothelial growth factor release

Background

Platelet-rich plasma (PRP) contains pro-angiogenic growth factors including vascular endothelial growth factor (VEGF). Angiogenesis is a necessary component of wound healing in instances of diabetic foot ulcers (DFU). PRP composition varies depending on methods and donor health status. Our group has developed an improved PRP protocol for diabetes treatment. The aims of this study were to examine the levels of the pro-angiogenic factor VEGF in these patient populations with and without diabetes.

Methods

PRP was prepared using 24 mL of whole blood from 13 diabetic and 10 non-diabetic patients registered at Klinik Hayandra. Whole blood in sodium citrate tubes were centrifuged at 1,000 rpm for 5 minutes followed by plasma separation. Plasma samples were centrifuged at 3,000 rpm for 5 minutes. Upper platelet-poor plasma layers were discarded, leaving 5 mL of concentrated platelet containing plasma (PRP). Concentrated plasma samples were mixed, aliquoted, stored at -86 °C, and pooled for platelet count, VEGF, and total protein analyses. Platelet counting was also performed using fresh whole blood and PRP to measure changes following PRP preparation.

Results

Diabetic donors had higher whole blood platelet counts than non-diabetic donors, but this difference was not statistically significant. An average increase of more than 250% in platelet number after PRP preparation using our method was noted in both groups. Freezing-thawing samples at -86 °C lysed more than 90% of PRP platelets regardless of diabetes status. Diabetic PRP had lower mean total protein and higher VEGF concentrations. Lysed platelets from diabetic donors released more VEGF than those from non-diabetic donors.

Conclusions

PRP from diabetic donors had higher VEGF content making autologous PRP application a promising treatment for DFU. However, this should be investigated another appropriate clinical trial.

Antimicrobial action of autologous platelet-rich plasma on MRSA-infected skin wounds in dogs

Effective antimicrobial preparations, other than antibiotics, are important for the treatment of potentially fatal drug-resistant infections. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of hospital-acquired and post- operative infections. Fortunately, the antimicrobial properties of platelet-rich plasma (PRP) against various microorganisms enable its potential use as an alternative to conventional antibiotics. The present work was designed to evaluate the hypothesized antimicrobial activity of PRP against MRSA infected skin wounds. Six adult male dogs were divided equally into control and PRP groups. Unilateral circular full-thickness skin wounds were created then a MRSA suspension was injected locally. Treatment started at 1st week post infection with subcutaneous infiltration of autologous activated PRP every week in the PRP group and with topical application of clindamycin cream twice daily in the control group. PRP decreased wound size and significantly increased wound contractility and re-epithelization, as confirmed by histopathological and immunohistochemical findings. Also PRP treated group showed significant decrease in ROS and redox imbalance with over expression of the TNF-α and VEGFA genes that indicate angiogenesis and maximum antibacterial activity after three weeks. In conclusion, CaCl₂-activated PRP exhibited antimicrobial activity against MRSA infection, which improved the infected wound healing re-epithelization and granulation tissue formation.

The effects of the use of platelet-rich plasma gel on local recurrence in an animal model of human fibrosarcoma

Background

Platelet-rich-plasma (PRP) is largely used, thanks to its properties, as wound therapy after surgical resection. Several studies and clinical findings have demonstrated that the PRP can accelerate the regeneration and the repair of tissues through the action of the platelet-derived growth factors.

Material and methods

Our study aimed to investigate the effects of PRP-gel on the rate of tumor relapse by using a mouse model of Human Fibrosarcoma (HF). The radical resection of tumors of mice was conducted under fluorescence-guidance (FGR) by using MacroFluo microscope, after a primary tumor removal with bright-light surgery (BLS).

Results

It was found that the lesion recurrence and the tumor growth were reduced in mice treated with PRP observed in each group of treatment (50%) after 30 days from tumor excision, respect to controls (without statistical significance; p = 0.12). The histopathological and immune-histochemical analysis did not report differences in cellular morphology between the tumors of control and PRP-treated mice.

Conclusion

Our data suggest that PRP-gel, used as an adjuvant treatment for the stimulation of tissue repair and speed up recovery, can impair tumor growth and slow the tumor.

Efficacy of Autologous Platelet-Rich Gel for Diabetic Foot Wound Healing: A Meta-Analysis of 15 Randomized Controlled Trials

Objectives: The meta-analysis was performed to summarize the available evidence and determine the healing effectiveness of autologous platelet-rich gel (APG) on diabetic foot (DF) wounds. Approach: PubMed and The Cochrane Library and CNKI databases were searched to identify prior randomized controlled trials. Methodological qualities of included studies were assessed using Cochrane Handbook for Systematic Reviews of Intervention. Healing rate was considered the primary outcome; the secondary outcomes included healing time and adverse events. Results: Fifteen studies involving a total of 827 subjects were analyzed in the meta-analysis. Considering the primary outcome, the average healing rate in APG group was 85.8% and ranged from 68.4% to 100%. Relatively, the control group was 57.4% and ranged from 18.2% to 75.0%. Eligible studies were compared with a fixed effects model (I ² = 0.0%, p = 0.496), indicating a higher healing rate with APG (risk ratio [RR] 1.44, 95% confidence interval [CI]: 1.32-1.57, z = 8.50, p < 0.001). The leave-one-out sensitivity analysis is robust. Considering the secondary outcomes, APG therapy needed less time (weighted mean difference -10.75 days, 95% CI: -11.67 to 8.86 days, z = 14.34, p < 0.001) and had fewer adverse events (RR 0.44, 95% CI: 0.25-0.76, z = 2.94, p = 0.003). Innovation: APG therapy is an innovative and effective approach to promote DF wound healing and reduce healing time and adverse events. Conclusion: The meta-analysis demonstrates that APG therapy has a positive effect on the treatment of DF wounds. However, additional well-designed and high-quality studies are needed to reach a conclusion with more confidence.

Review of Human Hair Follicle Biology: Dynamics of Niches and Stem Cell Regulation for Possible Therapeutic Hair Stimulation for Plastic Surgeons

Plastic surgeons are frequently asked to manage male- and female-pattern hair loss in their practice. This article discusses the epidemiology, pathophysiology, and current management of androgenetic alopecia and emphasizes more recent knowledge of stem cell niches in hair follicles that drive hair cycling, alopecia, and its treatment. The many treatment programs available for hair loss include newer strategies that involve the usage of growth factors, platelet-rich plasma, and fat to stimulate follicle growth. Future research may clarify novel biomolecular mechanisms that target specific cells that promote hair regeneration.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Platelet-rich plasma enhances adipose-derived stem cell-mediated angiogenesis in a mouse ischemic hindlimb model

AIM

To evaluate the angiogenic effect of platelet-rich plasma (PRP)-preconditioned adipose-derived stem cells (ADSCs) both in vitro and in a mouse ischemic hindlimb model.

METHODS

ADSCs were divided based on culture medium: 2.5% PRP, 5% PRP, 7.5% PRP, and 10% PRP. Cell proliferation rate was analyzed using the MTS assay. The gene expression of CD31, vascular endothelial growth factor, hypoxia-inducible factors, and endothelial cell nitric oxide synthase was analyzed using reverse transcription polymerase chain reaction. Cell markers and structural changes were assessed through immunofluorescence staining and the tube formation assay. Subsequently, we studied the in vivo angiogenic capabilities of ADSCs by a mouse ischemic hindlimb model.

RESULTS

The proliferation rate of ADSCs was higher in the 2.5%, 5%, and 7.5% PRP groups. The expression of hypoxia-inducible factor, CD31, vascular endothelial growth factor, and endothelial cell nitric oxide synthase in the 5% and 7.5% PRP groups increased. The 5%, 7.5%, and 10% PRP groups showed higher abilities to promote both CD31 and vascular endothelial growth factor production and tubular structure formation in ADSCs. According to laser Doppler perfusion scan, the perfusion ratios of ischemic limb to normal limb were significantly higher in 5% PRP, 7.5% PRP, and human umbilical vein endothelial cells groups compared with the negative control and fetal bovine serum (FBS) groups (0.88 ± 0.08, 0.85 ± 0.07 and 0.81 ± 0.06 for 5%, 7.5% PRP and human umbilical vein endothelial cells compared with 0.42 ± 0.17 and 0.54 ± 0.14 for the negative control and FBS, P < 0.01).

CONCLUSION

PRP-preconditioned ADSCs presented endothelial cell characteristics in vitro and significantly improved neovascularization in ischemic hindlimbs. The optimal angiogenic effect occurred in 5% PRP- and 7.5% PRP-preconditioned ADSCs.

Patient-Specific Bioinks for 3D Bioprinting of Tissue Engineering Scaffolds

Bioprinting has emerged as a promising tool in tissue engineering and regenerative medicine. Various 3D printing strategies have been developed to enable bioprinting of various biopolymers and hydrogels. However, the incorporation of biological factors has not been well explored. As the importance of personalized medicine is becoming more clear, the need for the development of bioinks containing autologous/patient-specific biological factors for tissue engineering applications becomes more evident. Platelet-rich plasma (PRP) is used as a patient-specific source of autologous growth factors that can be easily incorporated to hydrogels and printed into 3D constructs. PRP contains a cocktail of growth factors enhancing angiogenesis, stem cell recruitment, and tissue regeneration. Here, the development of an alginate-based bioink that can be printed and crosslinked upon implantation through exposure to native calcium ions is reported. This platform can be used for the controlled release of PRP-associated growth factors which may ultimately enhance vascularization and stem cell migration.

Injectable Mussel-Inspired Immobilization of Platelet-Rich Plasma on Microspheres Bridging Adipose Micro-Tissues to Improve Autologous Fat Transplantation by Controlling Release of PDGF and VEGF, Angiogenesis, Stem Cell Migration

Platelets-rich plasma (PRP) can produce growth factors (GFs) to improve angiogenesis. However, direct injection of PRP does not lead to highly localized GFs. The current study employs a mussel-inspired polydopamine to immobilize PRP on gelatin microspheres (GMs) with the purpose of bridging adipose micro-tissues to help implanted fat survive (GM-pDA-PRP). Enhanced PRP adhesion leads to a prolonged and localized production of GFs, which is verified by platelet counting and by ELISA of vascular endothelial growth factors (VEGFs) and of platelet derived growth factors (PDGFs). The GM-pDA-PRP "hatches" a microenvironment for the proliferation of adipose-derived stem cells. After the adipose micro-tissue has bridged with GM-pDA-PRP after 16 weeks, triple-fluorescence staining reveals that the mature adipocytes, blood vessels, and capillaries are arranged like in normal adipose tissue. The survival fat increases significantly compared to that in control, PRP, and GM-PRP groups (84.8 ± 11.4% versus 47.8 ± 8.9%, 56.9 ± 9.7%, and 60.2 ± 10.5%, respectively). Both histological assessments and CD31 immunofluorescence indicate that the improvement of angiogenesis in GM-pDA-PRP is higher than in the fat graft group (6.4-fold in quantitative CD31 positive cells). The CD34 positive cells in the GM-pDA-PRP group are around 3.5-fold the amount in the fat graft group, which suggests that more stem cells migrate to the implant area. Cell proliferation staining shows that the number of Ki67 positive cells is around five times as high as that in the fat graft group.

Enhancement of abdominal wall defect repair using allogenic platelet-rich plasma with commercial polyester/cotton fabric (Damour) in a canine model

Platelet-rich plasma (PRP) has an important role in musculoskeletal surgery; however, it has been underutilized for accelerating the healing of abdominal wall defects in veterinary practice. Therefore, the aim of this study was to evaluate the use of commercial polyester/cotton fabric (Damour) as a new composite mesh for the repair of experimentally induced abdominal wall defects in canine models, and to investigate the possible role of PRP for improving such repair and reducing allied complications. For this purpose, abdominal wall defects were created in 24 healthy mongrel dogs and then repaired with mesh alone (control group) or mesh and allogenic PRP (PRP group). Dogs were euthanized after 2 or 4 months for gross examination of implantation site, detection of adhesion score and hernia recurrence. Moreover, tissue samples were collected for histological and gene expression analyses for neovascularization, collagen formation and tissue incorporation. Hernia recurrence was not recorded in PRP-treated dogs that also displayed significantly more neovascularization and less severe adhesion to the underlings (1.08 ± 0.51) in comparison to control group (2.08 ± 0.99). Histological and molecular evaluation confirmed the gross findings that collagen deposition, new vessel formation, and overexpression of angiogenic and myofibroplastic genes (COL1α1, COL3α1, VEGF and TGFβ1) were observed more frequently in the PRP group, at both time points. In conclusion, we found that addition of allogenic PRP to Damour mesh enhanced neovessel formation, and increased tissue deposition and incorporation, with subsequent reduction of peritoneal adhesion and recurrence rate.

Effects of platelet rich plasma on fascial healing in rats with fecal peritonitis

PURPOSE

To evaluate the effects of platelet rich plasma (PRP) on the healing of fascia wherein peritonitis has been created.

METHODS

Twenty eight Wistar Albino rats were divided into four groups. Only a primary fascial repair following laparotomy was performed on Group 1, a primary fascial repair performed and PRP treatment applied following laparotomy on Group 2, and a fecal peritonitis created following laparotomy and a primary fascial repair carried out on Group 3. A fecal peritonitis was created following laparotomy and primary fascial repair and PRP treatment on the fascia was carried out on Group 4.

RESULTS

TNF-α was found to be significantly lower in the control group (Group 1). It was detected at the highest level in the group in which fecal peritonitis was created and PRP applied (Group 4). TGF-β was determined as being significantly higher only in Group 4. Histopathologically, the differences between the groups in terms of cell infiltration and collagen deposition were not found to be significant.

CONCLUSION

When platelet rich plasma was given histologically and biochemicaly as wound healing parameters cellular infiltration, collagen accumulation, and tissue hydroxyiproline levels were not increased but neovascularization, fibroblast activation and TNF Alfa levels were increased and PRP accelerated wound healing.

Synergistic effects of HBO and PRP improve bone regeneration with autologous bone grafting

Bone defects remain a challenge for patients and orthopaedic surgeons. Autologous transfer of cancellous bone grafts remains the standard of care. However, in recent years various osteoinductive substitute materials, such as platelet rich plasma (PRP) and hyperbaric oxygen therapy (HBO) have been shown to improve bone healing. This study evaluates the effects of a combined application of PRP and HBO with autologous bone grafting in an animal model. In 48 New Zealand White rabbits bone defects at the radius were filled with autologous bone harvested at the iliac crest. This was combined with application of autologous PRP and/or HBO treatment for the duration of this study. After 3 and 6 weeks histomorphometric, immunohistochemical and radiologic evaluations were performed. All animals tolerated the treatment well. Improved bone regeneration was shown in all groups at 6 weeks compared to 3 weeks. Additional application of PRP and HBO resulted in an increase in new bone formation and increased neovascularization at 3 and 6 weeks. There was no statistical significant difference between PRP and HBO application in these regards. A combinatory use of PRP and HBO resulted in an increased bone regeneration and neovascularization compared to all other groups. This study provides evidence for an improvement of bone regeneration with the combinatory application of PRP and HBO to autologous cancellous bone grafts in a model of weight bearing bone defects in rabbits. Also synergistic effects of these two measures on angiogenesis were evident.

Evaluation of wound healing in diabetic foot ulcer using platelet-rich plasma gel: A single-arm clinical trial

The aim of the present study was to evaluate the effectiveness of using autologous platelet-rich plasma (PRP) gel for treatment of diabetic foot ulcer (DFU) during the first 4 weeks of the treatment. In this longitudinal and single-arm trial, 100 patients were randomly selected after meeting certain inclusion and exclusion criteria; of these 100 patients, 70 (70%) were enrolled in the trial. After the primary care actions such as wound debridement, the area of each wound was calculated and recorded. The PRP therapy (2mL/cm² of ulcers) was performed weekly until the healing time for each patient. We used one sample T-test for healing wounds and Bootstrap resampling approach for reporting confidence interval with 1000 Bootstrap samples. The p-value<0.05 were considered statistically significant. The mean (SD) of DFU duration was 19.71 weeks (4.94) for units sampling. The ratio of subjects who withdrew from the study was calculated to be 2 (2.8%). Average area of 71 ulcers in the mentioned number of cases was calculated to be 6.11cm² (SD: 4.37). Also, the mean, median (SD) of healing time was 8.7, 8 weeks (SD: 3.93) except for 2 mentioned cases. According to one sample T-test, wound area (cm²), on average, significantly decreased to 51.9% (CI: 46.7-57.1) through the first four weeks of therapy. Furthermore, significant correlation (0.22) was not found between area of ulcers and healing duration (p-value>0.5). According to the results, PRP could be considered as a candidate treatment for non-healing DFUs as it may prevent future complications such as amputation or death in this pathological phenomenon.

Platelet-Rich Plasma: The Choice of Activation Method Affects the Release of Bioactive Molecules

Platelet-Rich Plasma (PRP) is a low-cost procedure to deliver high concentrations of autologous growth factors (GFs). Platelet activation is a crucial step that might influence the availability of bioactive molecules and therefore tissue healing. Activation of PRP from ten voluntary healthy males was performed by adding 10% of CaCl₂, 10% of autologous thrombin, 10% of a mixture of CaCl₂ + thrombin, and 10% of collagen type I. Blood derivatives were incubated for 15 and 30 minutes and 1, 2, and 24 hours and samples were evaluated for the release of VEGF, TGF-β1, PDGF-AB, IL-1β, and TNF-α. PRP activated with CaCl₂, thrombin, and CaCl₂/thrombin formed clots detected from the 15-minute evaluation, whereas in collagen-type-I-activated samples no clot formation was noticed. Collagen type I produced an overall lower GF release. Thrombin, CaCl₂/thrombin, and collagen type I activated PRPs showed an immediate release of PDGF and TGF-β₁ that remained stable over time, whereas VEGF showed an increasing trend from 15 minutes up to 24 hours. CaCl₂ induced a progressive release of GFs from 15 minutes and increasing up to 24 hours. The method chosen to activate PRP influences both its physical form and the releasate in terms of GF amount and release kinetic.

Effects of Platelet-Rich Plasma (PRP) on a Model of Renal Ischemia-Reperfusion in Rats

Renal ischemia-reperfusion injury is a major cause of acute renal failure, causing renal cell death, a permanent decrease of renal blood flow, organ dysfunction and chronic kidney disease. Platelet-rich plasma (PRP) is an autologous product rich in growth factors, and therefore able to promote tissue regeneration and angiogenesis. This product has proven its efficacy in multiple studies, but has not yet been tested on kidney tissue. The aim of this work is to evaluate whether the application of PRP to rat kidneys undergoing ischemia-reperfusion reduces mid-term kidney damage. A total of 30 monorrenal Sprague-Dawley male rats underwent renal ischemia-reperfusion for 45 minutes. During ischemia, PRP (PRP Group, n = 15) or saline solution (SALINE Group, n = 15) was administered by subcapsular renal injection. Control kidneys were the contralateral organs removed immediately before the start of ischemia in the remaining kidneys. Survival, body weight, renal blood flow on Doppler ultrasound, kidney weight, kidney volume, blood biochemistry and histopathology were determined for all subjects and kidneys, as applicable. Correlations between these variables were searched for. The PRP Group showed significantly worse kidney blood flow (p = 0.045) and more histopathological damage (p<0.0001). Correlations were found between body weight, kidney volume, kidney weight, renal blood flow, histology, and serum levels of creatinine and urea. Our study provides the first evidence that treatment with PRP results in the deterioration of the kidney’s response to ischemia-reperfusion injury.

Testosterone and Voluntary Exercise Promote Angiogenesis in Hearts of Rats with Diabetes by Enhancing Expression of VEGF-A and SDF-1a

OBJECTIVES

Impaired angiogenesis in cardiac tissue is a major complication of diabetes. This study was aimed to evaluate the effects of testosterone and voluntary exercise on vascular endothelial growth factor-A (VEGF-A), stromal cell-derived factor 1a (SDF-1a) and myocardial capillary density in heart of rats with diabetes.

METHODS

Type 1 diabetes was induced by intraperitoneal injection of 55 mg/kg of streptozotocin in 80 male Wistar rats. After 42 days of treatment with testosterone (2 mg/kg/day) or voluntary exercise alone or in combination, angiogenesis was determined in the hearts by immunostaining for PECAM-1/CD31. The expressions of VEGF-A and SDF-1a levels in heart were also determined by the ELISA method.

RESULTS

Our results showed that capillary density, VEGF-A and SDF-1a levels in the heart were significantly decreased in castrated rats with diabetes, whereas these effects were reversed by testosterone and exercise. Furthermore, simultaneous treatment of castrated rats with diabetes with testosterone and exercise had a synergistic effect on capillary density, VEGF-A and SDF-1a levels in the heart. In the group with diabetes, either testosterone or exercise increased capillary density, VEGF-A and SDF-1a protein levels in heart tissue. However, the effects of combination therapy in rats with diabetes with testosterone and exercise on capillary density, VEGF-A and SDF-1a levels in the heart was synergistic.

CONCLUSIONS

Our findings suggest that testosterone and exercise can promote neoangiogenesis in rats with diabetes and in castrated rats with diabetes. The proangiogenesis effect of testosterone and exercise is associated with the enhanced expression of VEGF-A and SDF-1a in heart tissue.

Platelet-Rich Plasma-Loaded Poly(d,l-lactide)-Poly(ethylene glycol)-Poly(d,l-lactide) Hydrogel Dressing Promotes Full-Thickness Skin Wound Healing in a Rodent Model

Traditional therapeutic methods for skin wounds have many disadvantages, and new wound dressings that can facilitate the healing process are thus urgently needed. Platelet-rich plasma (PRP) contains multiple growth factors (GFs) and shows a significant capacity to heal soft tissue wounds. However, these GFs have a short half-life and deactivate rapidly; we therefore need a sustained delivery system to overcome this shortcoming. In this study, poly(d,l-lactide)-poly(ethylene glycol)-poly(d,l-lactide) (PDLLA-PEG-PDLLA: PLEL) hydrogel was successfully created as delivery vehicle for PRP GFs and was evaluated systematically. PLEL hydrogel was injectable at room temperature and exhibited a smart thermosensitive in situ gel-formation behavior at body temperature. In vitro cell culture showed PRP-loaded PLEL hydrogel (PRP/PLEL) had little cytotoxicity, and promoted EaHy926 proliferation, migration and tube formation; the factor release assay additionally indicated that PLEL realized the controlled release of PRP GFs for as long as 14 days. When employed to treat rodents’ full-thickness skin defects, PRP/PLEL showed a significantly better ability to raise the number of both newly formed and mature blood vessels compared to the control, PLEL and PRP groups. Furthermore, the PRP/PLEL-treated group displayed faster wound closure, better reepithelialization and collagen formation. Taken together, PRP/PLEL provides a promising strategy for promoting angiogenesis and skin wound healing, which extends the potential of this dressing for clinical application.

Regulating VEGF signaling in platelet concentrates via specific VEGF sequestering

Platelets contain an abundance of growth factors that mimic the composition of the wound healing milieu, and platelet-derived VEGF in particular can negatively influence wound healing if unregulated. Here, we sought to capture and regulate the activity of VEGF factor from human platelets using poly(ethylene glycol) microspheres. In this communication, we demonstrate that platelet freeze/thaw produced significantly higher levels of Vascular Endothelial Growth Factor (VEGF) than either calcium chloride treatment, protease activated receptor 1 activating peptide (PAR1AP) treatment, or thrombin treatment. PEG microspheres containing a VEGF-binding peptide (VBP), derived from VEGFR2, sequestered VEGF from platelet concentrate, prepared via freeze/thaw, and reduced the bioactivity of platelet concentrate in HUVEC culture, which suggests that VBP microspheres sequestered and reduced the activity of VEGF from patient-derived platelets. Here, we demonstrate the ability of VEGF sequestering microspheres to regulate the activity of VEGF derived from a growth factor-rich autologous human blood product.

Platelet lysate-based pro-angiogenic nanocoatings

Human platelet lysate (PL) is a cost-effective and human source of autologous multiple and potent pro-angiogenic factors, such as vascular endothelial growth factor A (VEGF A), fibroblast growth factor b (FGF b) and angiopoietin-1. Nanocoatings previously characterized were prepared by layer-by-layer assembling incorporating PL with marine-origin polysaccharides and were shown to activate human umbilical vein endothelial cells (HUVECs). Within 20 h of incubation, the more sulfated coatings induced the HUVECS to the form tube-like structures accompanied by an increased expression of angiogenic-associated genes, such as angiopoietin-1 and VEGF A. This may be a cost-effective approach to modify 2D/3D constructs to instruct angiogenic cells towards the formation of neo-vascularization, driven by multiple and synergistic stimulations from the PL combined with sulfated polysaccharides.

STATEMENT OF SIGNIFICANCE

The presence, or fast induction, of a stable and mature vasculature inside 3D constructs is crucial for new tissue formation and its viability. This has been one of the major tissue engineering challenges, limiting the dimensions of efficient tissue constructs. Many approaches based on cells, growth factors, 3D bioprinting and channel incorporation have been proposed. Herein, we explored a versatile technique, layer-by-layer assembling in combination with platelet lysate (PL), that is a cost-effective source of many potent pro-angiogenic proteins and growth factors. Results suggest that the combination of PL with sulfated polyelectrolytes might be used to introduce interfaces onto 2D/3D constructs with potential to induce the formation of cell-based tubular structures.

In vitro immunological and biological evaluations of the angiogenic potential of platelet-rich fibrin preparations: a standardized comparison with PRP preparations

Background

Platelet-rich fibrin (PRF), a platelet-rich plasma (PRP) derivative mainly composed of fibrin networks, has been increasingly demonstrated to be effective in wound healing in clinical and pre-clinical animal studies. However, there has still been a concern that major growth factors may significantly be loss from PRF during its preparation through the slow clotting process. To address this concern, we compared the angiogenic potential of PRF and PRP by standardization of procedures based on volume ratios.

Methods

PRP, PRF, and platelet-poor plasma (PPP) were prepared from the peripheral blood of healthy donors. PRF preparations were squeezed or homogenized to produce exudate (PRFexu) or extract (PRFext), respectively. Concentrations of the angiogenic factors and their bioactivities were determined using ELISA kits, a scratch assay using endothelial cells and a chicken chorioallantoic membrane (CAM) assay.

Results

In PRP and PRF preparations, both VEGF and PDGF-BB were significantly more concentrated than PPP. In the scratch assay, PRFexu and PRFext were the most effective for wound closure. In the CAM assay, PRF membranes were the most effective for neovascularization.

Conclusions

It is suggested that PRF preparations efficiently preserve the angiogenic factors and function not only as a scaffolding material but as a reservoir of angiogenic factors in wound healing.

Protective Effect of Platelet Rich Plasma on Experimental Ischemia/Reperfusion Injury in Rat Ovary

BACKGROUND/AIMS

Ovarian torsion is a common cause of local ischemic damage, reduced follicular activity and infertility. Platelet-rich plasma (PRP) contains growth factors with demonstrated cytoprotective properties; so we evaluated PRP efficacy in a rat ischemia/reperfusion (I/R) model.

METHODS

Sixty adult female Sprague-Dawley albino rats were randomly assigned to 6 groups of 8 animals each: Sham, Ischemia, I/R, Sham + PRP, I + PRP and I/R + PRP; and the remaining 12 used to prepare PRP. Ischemia groups were subjected to bilateral adnexal torsion for 3 h, while I/R and I/R + PRP groups received subsequent detorsion for 3 h. Intraperitoneal PRP was administered 30 min prior to ischemia (Ischemia + PRP) or reperfusion (I/R + PRP).

RESULTS

Total oxidant status (TOS), oxidative stress index (OSI) and total ovarian histopathological scores were higher in Ischemia and I/R groups than in the Sham group (p < 0.05). PRP decreased mean TOS, OSI and histopathological scores in I + PRP and I/R + PRP groups compared to the corresponding Ischemia and I/R groups (p < 0.001). There was a strong correlation between total histopathological score and OSI (r = 0.877, p < 0.001). Peritoneal vascular endothelial growth factor was significantly higher in PRP-treated groups than corresponding untreated groups (p < 0.05).

CONCLUSION

PRP is effective for the prevention of ischemia and reperfusion damage in rat ovary.

Effect of platelet-rich plasma on the healing of cutaneous defects exposed to acute to chronic wounds: a clinico-histopathologic study in rabbits

Background

Platelet-rich plasma (PRP) contains numerous growth factors to promote wound healing and angiogenesis. The aim of this study was to gain further information about the benefits of platelet-rich-plasma for healing cutaneous acute to chronic wounds.

Methods

A total of 30 New Zealand albino rabbits (n = 15/group) were randomly assigned to two experimental groups: control group, and PRP group. Bilateral resection defects measuring 3 cm were surgically created on the dorsolateral of the cutaneous in animals and the defects were randomly divided into two mentioned groups. Wound area, neovascularization, size and epithelialization were compared on days 7, 14 and 21 post-wounding. Histopathological analyses were conducted on 15 specimens from each group after sacrifice by the cellular aspects of the regeneration of the tissue.

Results

Our results were indicated that the wound area of PRP was smaller than that in the non-treated group on days 7, 14 and 21. Furthermore, a significant decrease of the wound size was observed in PRP groups that were significantly greater than that in the control group. A significant increase of the mean vascular density was noted in the PRP treated groups compared to the control groups at day 14 and especially day 21. This results indicated that PRP treated group’ enhanced angiogenesis at the wound beds as compared to no treatment group.

Conclusion

These results could be useful for researchers in the growing fields of tissue repair and experimental wound healing. Further studies will be essential to determine the role of PRP in clinical practice.

Platelet-Rich Plasma Promotes Axon Regeneration, Wound Healing, and Pain Reduction: Fact or Fiction

Platelet-rich plasma (PRP) has been tested in vitro, in animal models, and clinically for its efficacy in enhancing the rate of wound healing, reducing pain associated with injuries, and promoting axon regeneration. Although extensive data indicate that PRP-released factors induce these effects, the claims are often weakened because many studies were not rigorous or controlled, the data were limited, and other studies yielded contrary results. Critical to assessing whether PRP is effective are the large number of variables in these studies, including the method of PRP preparation, which influences the composition of PRP; type of application; type of wounds; target tissues; and diverse animal models and clinical studies. All these variables raise the question of whether one can anticipate consistent influences and raise the possibility that most of the results are correct under the circumstances where PRP was tested. This review examines evidence on the potential influences of PRP and whether PRP-released factors could induce the reported influences and concludes that the preponderance of evidence suggests that PRP has the capacity to induce all the claimed influences, although this position cannot be definitively argued. Well-defined and rigorously controlled studies of the potential influences of PRP are required in which PRP is isolated and applied using consistent techniques, protocols, and models. Finally, it is concluded that, because of the purported benefits of PRP administration and the lack of adverse events, further animal and clinical studies should be performed to explore the potential influences of PRP.

Use of platelet-rich plasma to reinforce the staple line during laparoscopic sleeve gastrectomy: feasibility study and preliminary outcome

AIMS

Reinforcement of the staple line is one of the most debated technical aspects concerning laparoscopic sleeve gastrectomy (LSG). Different buttressing methods have been proposed and demonstrated to be effective in reducing the incidence of staple line bleeding, although data concerning their effort on staple line leakage are not consistent. The aim of this study was to ascertain the technical feasibility and to report the preliminary outcomes of laparoscopic use of platelet-rich plasma (PRP) to reinforce the staple line during sleeve gastrectomy.

PATIENTS AND METHODS

From March 2012 to May 2012, 20 patients were prospectively enrolled (10 females; mean age, 44.6 ± 11 years; mean body mass index, 42.3 ± 5.45 kg/m(2)). Type 2 diabetes mellitus was present in 4 patients, obstructive sleep apnea syndrome in 3, and hypertension in 6. LSG was performed using a 48-French bougie and gold cartridges; reinforcement of the staple lines with buttressed materials or oversewing the suture was performed excluding the last cranial cartridge. PRP was prepared by separating the platelets from autologous blood withdrawn on the same day of surgery, in order to obtain a membrane with cylindrical shape (2×5 cm) formed by fibrin and active platelets. The membrane is introduced through the 10-mm trocar and placed at the upper portion of the staple line. The overall cost for the preparation of PRP is about €15.

RESULTS

No intraoperative complications and conversions have been recorded during the surgical procedures. No deaths occurred. The mean operative time was 85 ± 31 minutes, which was not significantly increased compared with the operative time of the surgeon's overall personal series (750 cases). At 12 months of follow-up the abdominal ultrasound was negative for collections, and upper contrast showed no images indicating gastric leaks. In no case did PRP induce symptoms of rejection, infection, or adverse events.

CONCLUSIONS

The use of PRP during LSG is feasible, does not increase significantly the operative time, does not require any special devices, and is cost effective. A larger cohort of patients is needed to ascertain the potential effectiveness of PRP in the prevention of postoperative staple line complications.

Effect of platelet-rich plasma with self-assembled peptide on the rotator cuff tear model in rat

Several trials have been carried out to improve the healing of rotator cuff tear, but their effects remain controversial. In this study, we examined the therapeutic effect of platelet-rich plasma (PRP) in combination with self-assembled peptide (SAP) on the healing of rotator cuff tear in the rat. Twenty-seven Sprague-Dawley rats, aged 15 weeks, were used for the rotator cuff tear model. The supraspinatus muscle at the insertion site was dissected and truncated, leaving the cut edge free. A week after the surgery, the rats were randomly divided into SAP, PRP, SAP-PRP and control groups and 0.2 ml SAP, PRP, SAP-PRP and saline were injected, respectively. Bonar scores and synovial inflammation grade were checked 5 weeks after the injection. Immunofluorescence staining for heat shock protein (HSP)-70 and caspase-3 was conducted. Furthermore, maximum stride length was measured before and at 2 and 4 weeks after the injection. The Bonar scores were 6.4 ± 1.8 in the SAP group, 5.9 ± 2.0 in the PRP group, 4.7 ± 1.1 in the SAP-PRP group and 8.3 ± 2.3 in the control group. There was significant difference between the SAP-PRP and control groups in post hoc multiple comparison analysis. Among four categories of Bonar scores, collagen arrangement and vascular infiltration showed improvement after SAP-PRP injection. Immunofluorescence images showed that HSP-70 and caspase-3 were much less expressed in the SAP-PRP group than in the other groups. In conclusion, SAP-PRP can be effective in healing a rotator cuff tear by enhancing the collagen arrangement and inhibiting inflammatory changes and apoptosis. Copyright © 2015 John Wiley & Sons, Ltd.

Infiltration of plasma rich in growth factors enhances in vivo angiogenesis and improves reperfusion and tissue remodeling after severe hind limb ischemia

PRGF is a platelet concentrate within a plasma suspension that forms an in situ-generated fibrin-matrix delivery system, releasing multiple growth factors and other bioactive molecules that play key roles in tissue regeneration. This study was aimed at exploring the angiogenic and myogenic effects of PRGF on in vitro endothelial cells (HUVEC) and skeletal myoblasts (hSkMb) as well as on in vivo mouse subcutaneously implanted matrigel and on limb muscles after a severe ischemia. Human PRGF was prepared and characterized. Both proliferative and anti-apoptotic responses to PRGF were assessed in vitro in HUVEC and hSkMb. In vivo murine matrigel plug assay was conducted to determine the angiogenic capacity of PRGF, whereas in vivo ischemic hind limb model was carried out to demonstrate PRGF-driven vascular and myogenic regeneration. Primary HUVEC and hSkMb incubated with PRGF showed a dose dependent proliferative and anti-apoptotic effect and the PRGF matrigel plugs triggered an early and significant sustained angiogenesis compared with the control group. Moreover, mice treated with PRGF intramuscular infiltrations displayed a substantial reperfusion enhancement at day 28 associated with a fibrotic tissue reduction. These findings suggest that PRGF-induced angiogenesis is functionally effective at expanding the perfusion capacity of the new vasculature and attenuating the endogenous tissue fibrosis after a severe-induced skeletal muscle ischemia.