Blood-derived biomaterials and platelet growth factors in regenerative medicine

The effect of mesenchymal stem cells combined with platelet-rich plasma on skin wound healing

INTRODUCTION

Mesenchymal stem cells (MSCs) are multipotent stem cells that have the potential of proliferation, high self-renewal, and the potential of multilineage differentiation. The differentiation potential of the MSCs in vivo and in vitro has caused these cells to be regarded as potentially appropriate tools for wound healing. After the burn, trauma or removal of the tumor of wide wounds is developed. Although standard treatment for skin wounds is primary healing or skin grafting, they are not always practical mainly because of limited autologous skin grafting.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar, PubMed (NLM), LISTA (EBSCO), and Web of Science have been searched.

EVIDENCE SYNTHESIS

For clinical use of the MSCs in wound healing, two key issues should be taken into account: First, engineering biocompatible scaffolds clinical use of which leads to the least amount of side effects without any immunologic response and secondly, use of stem cells secretions with the least amount of clinical complications despite their high capability of healing damage.

CONCLUSION

In light of the MSCs' high capability of proliferation and multilineage differentiation as well as their significant role in modulating immunity, these cells can be used in combination with tissue engineering techniques. Moreover, the MSCs' secretions can be used in cell therapy to heal many types of wounds. The combination of MSCs and PRP aids wound healing which could potentially be used to promote wound healing.

Leucocyte and Platelet-rich Fibrin: a carrier of autologous multipotent cells for regenerative medicine

The wound healing is a complex process wherein inflammation, proliferation and regeneration evolve according to a spatio-temporal pattern from the activation of coagulation cascade to the formation of a plug clot including fibrin matrix, blood-borne cells and cytokines/growth factors. Creating environments conducive to tissue repair, the haemoderivatives are commonly proposed for the treatment of hard-to-heal wounds. Here, we explored in vitro the intrinsic regenerative potentialities of a leucocyte- and platelet-rich fibrin product, known as CPL-MB, defining the stemness grade of cells sprouting from the haemoderivative. Using highly concentrated serum-based medium to simulate wound conditions, we isolated fibroblast-like cells (CPL-CMCs) adhering to plastic and showing stable in vitro propagation, heterogeneous stem cell expression pattern, endothelial adhesive properties and immunomodulatory profile. Due to their blood derivation and expression of CXCR4, CPL-CMCs have been suggested to be immature cells circulating in peripheral blood at quiescent state until activation by both coagulation event and inflammatory stimuli such as stromal-derived factor 1/SDF1. Expressing integrins (CD49f, CD103), vascular adhesion molecules (CD106, CD166), endoglin (CD105) and remodelling matrix enzymes (MMP2, MMP9, MMP13), they showed a transendothelial migratory potential besides multipotency. Taken together, our data suggested that a standardized, reliable and economically feasible blood product such as CPL-MB functions as an artificial stem cell niche that, under permissive conditions, originate ex vivo immature cells that could be useful for autologous stem cell-based therapies.

The effects of platelet lysate patches on the activity of tendon-derived cells

Platelet-derived biomaterials are widely explored as cost-effective sources of therapeutic factors, holding a strong potential for endogenous regenerative medicine. Particularly for tendon repair, treatment approaches that shift the injury environment are explored to accelerate tendon regeneration. Herein, genipin-crosslinked platelet lysate (PL) patches are proposed for the delivery of human-derived therapeutic factors in patch augmentation strategies aiming at tendon repair. Developed PL patches exhibited a controlled release profile of PL proteins, including bFGF and PDGF-BB. Additionally, PL patches exhibited an antibacterial effect by preventing the adhesion, proliferation and biofilm formation by S. aureus, a common pathogen in orthopaedic surgical site infections. Furthermore, these patches supported the activity of human tendon-derived cells (hTDCs). Cells were able to proliferate over time and an up-regulation of tenogenic genes (SCX, COL1A1 and TNC) was observed, suggesting that PL patches may modify the behavior of hTDCs. Accordingly, hTDCs deposited tendon-related extracellular matrix proteins, namely collagen type I and tenascin C. In summary, PL patches can act as a reservoir of biomolecules derived from PL and support the activity of native tendon cells, being proposed as bioinstructive patches for tendon regeneration.

STATEMENT OF SIGNIFICANCE

Platelet-derived biomaterials hold great interest for the delivery of therapeutic factors for applications in endogenous regenerative medicine. In the particular case of tendon repair, patch augmentation strategies aiming at shifting the injury environment are explored to improve tendon regeneration. In this study, PL patches were developed with remarkable features, including the controlled release of growth factors and antibacterial efficacy. Remarkably, PL patches supported the activity of native tendon cells by up-regulating tenogenic genes and enabling the deposition of ECM proteins. This patch holds great potential towards simultaneously reducing post-implantation surgical site infections and promoting tendon regeneration for prospective in vivo applications.

Reflections on Dry Eye Syndrome Treatment: Therapeutic Role of Blood Products

Dry eye syndrome (DES) is a multifactorial, frequent, pathology characterized by deficient tear production or increased evaporation of tears and associated with ocular surface alteration and inflammation. It mostly affects, but not exclusively, older individuals and leads to varying degrees of discomfort and decreased quality of life. Although the typical treatments of DES rely on using artificial tears, polyunsaturated fatty acids, integrin antagonists, anti-inflammatory agents, or on performing punctal occlusion, recently, standardized blood-derived serum eye drops (SED) are generating much interest as a new physiological treatment option. The scientific rationale in using SED for treating or releasing the symptoms of DES is thought to lie in its composition in multiple factors that resembles that of tears and contributes to the healing and protection of the ocular surface. This manuscript seeks to provide relevant background information on the management of DES, and on the increasing role that various types of SED or platelet lysates, from autologous or allogeneic origins, are playing in the improved therapeutic management of this pathology. The increasing role played by blood establishments in producing better-standardized SED is also addressed.

An optimised protocol for platelet-rich plasma preparation to improve its angiogenic and regenerative properties

Although platelet-rich plasma (PRP) is used as a source of growth factors in regenerative medicine, its effectiveness remains controversial, partially due to the absence of PRP preparation protocols based on the regenerative role of platelets. Here, we aimed to optimise the protocol by analysing PRP angiogenic and regenerative properties. Three optimising strategies were evaluated: dilution, 4 °C pre-incubation, and plasma cryoprecipitate supplementation. Following coagulation, PRP releasates (PRPr) were used to induce angiogenesis in vitro (HMEC-1 proliferation, migration, and tubule formation) and in vivo (chorioallantoic membrane), as well as regeneration of excisional wounds on mouse skin. Washed platelet releasates induced greater angiogenesis than PRPr due to the anti-angiogenic effect of plasma, which was decreased by diluting PRPr with saline. Angiogenesis was also improved by both PRP pre-incubation at 4 °C and cryoprecipitate supplementation. A combination of optimising variables exerted an additive effect, thereby increasing the angiogenic activity of PRPr from healthy donors and diabetic patients. Optimised PRPr induced faster and more efficient mouse skin wound repair compared to that induced by non-optimised PRPr. Acetylsalicylic acid inhibited angiogenesis and tissue regeneration mediated by PRPr; this inhibition was reversed following optimisation. Our findings indicate that PRP pre-incubation at 4 °C, PRPr dilution, and cryoprecipitate supplementation improve the angiogenic and regenerative properties of PRP compared to the obtained by current methods.

The effects of gelatin, fibrin-platelet glue and their combination on healing of the experimental critical bone defect in a rat model: radiological, histological, scanning ultrastructural and biomechanical evaluation

Fibrin-platelet glue (FPG) is a blood derivative, in which platelets and fibrinogen are concentrated in a small plasma volume, by differential centrifugation and precipitation. It can form a three-dimensional and biocompatible fibrin scaffold with a myriad of growth factors and proteins that are released progressively to the local environment and contribute to the accelerated postoperative bone healing. Gelatin (Gel) is a derivative of collagen and can promote cell adhesion and proliferation due to its unique sequence of amino acids, so it is suitable for bone tissue applications. This study examined the effects of Gel, FPG and their combinations as bone scaffold on the healing of surgically created critical-size defects in rat radius. Fifty critical size defects of 5 mm long were bilaterally created in the radial diaphysis of 25 rats. The animals were randomly divided into five equal groups as empty defect, autograft, Gel, FPG and Gel-FPG groups (n = 10 in each group). Radiographs of each forelimb were taken postoperatively on the 1st day and then at the 28th and 56th days post injury to evaluate bone formation, union and remodeling of the defect. After 56 days, the rats were euthanized and their harvested healing bone samples were evaluated by histopathology, scanning electron microscopy (SEM) and biomechanical testing. The results of present study showed that the Gel alone did not significantly affect bone healing and regeneration; however, the Gel treated defects promoted healing more than those that were left untreated (negative control). Furthermore, the FPG-enhanced grafts provided a good scaffold containing numerous growth factors for proliferation of osteoinduction and was effective in improving the structural and functional properties of the newly formed bone more than that of the untreated and also the Gel treated groups. Incorporation of Gel into the FPG scaffold improved healing potential of the FPG scaffold; however, it was still inferior to the autograft (positive control). Although the Gel-FPG scaffolds had best effectiveness during bone regeneration, it still needs to be further enhanced by incorporation of the ceramic and osteoinductive biomaterials.

Opening new horizons in regenerative dermatology using platelet-based autologous therapies

Biological therapeutic therapies are gaining the attention of scientists and medical doctors. Accumulating evidence suggests that blood-derived autologous therapies are safe and effective treatments for skin repair and wound healing. The fibrin network formed after plasmatic activation and the autologous growth factors released when platelets degranulate constitute a real biological medicine that has been shown to promote cell recruitment, stimulate new blood vessel formation, reduce inflammation as well as protect from local infections. This perspective highlights recent basic and clinical results published on blood-derived autologous therapies in the field of regenerative dermatology and discusses potential challenges and future prospects.

Comparison of three human platelet lysates used as supplements for in vitro expansion of corneal endothelium cells

BACKGROUND

Human platelet lysates (HPLs) are emerging as the new gold standard supplement of growth media for ex vivo expansion of cells for transplant. However, variations do exist in the way how HPLs are prepared. In particular, uncertainties still exist regarding the type of HPL most suitable for corneal endothelium cells (CEC) expansion, especially as these cells have limited proliferative capacity.

MATERIAL AND METHODS

Three distinct HPL preparations were produced, with or without calcium chloride/glass beads activation, and with or without heat treatment at 56°C for 30min. These HPLs were used to supplement basal D-MEM growth medium, each at a protein concentration equivalent to that of 10% fetal bovine serum (FBS; control). Impact on CEC (BCE C/D-1b cells) in vitro morphology, viability and capacity to express Zonula occludens-1 (ZO-1) tight junction marker was assessed by Western blotting.

RESULTS

BCE C/D-1b cells grown in all HPL supplements exhibited four of essential characteristic properties: adhesion capacity, microscopic morphology and viability similar to that observed when using 10% FBS. In addition, Western blots analysis revealed an expression of the ZO-1 marker by BCE C/D-1b cells in all conditions of culture.

CONCLUSION

CECs can expand ex vivo in a basal medium supplemented with the three HPLs without noticeable difference compared to FBS supplement. These data support further studies to evaluate the potential to use HPLs as a clinical-grade xeno-free supplement of CEC for corneal transplant.

Adipose Extracellular Matrix/Stromal Vascular Fraction Gel Secretes Angiogenic Factors and Enhances Skin Wound Healing in a Murine Model

Mesenchymal stem cells are an attractive cell type for cytotherapy in wound healing. The authors recently developed a novel, adipose-tissue-derived, injectable extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel) for stem cell therapy. This study was designed to assess the therapeutic effects of ECM/SVF-gel on wound healing and potential mechanisms. ECM/SVF-gel was prepared for use in nude mouse excisional wound healing model. An SVF cell suspension and phosphate-buffered saline injection served as the control. The expression levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and monocyte chemotactic protein-1 (MCP-1) in ECM/SVF-gel were analyzed at different time points. Angiogenesis (tube formation) assays of ECM/SVF-gel extracts were evaluated, and vessels density in skin was determined. The ECM/SVF-gel extract promoted tube formation in vitro and increased the expression of the angiogenic factors VEGF and bFGF compared with those in the control. The expression of the inflammatory chemoattractant MCP-1 was high in ECM/SVF-gel at the early stage and decreased sharply during the late stage of wound healing. The potent angiogenic effects exerted by ECM/SVF-gel may contribute to the improvement of wound healing, and these effects could be related to the enhanced inflammatory response in ECM/SVF-gel during the early stage of wound healing.

A review of fibrin and fibrin composites for bone tissue engineering

Tissue engineering has emerged as a new treatment approach for bone repair and regeneration seeking to address limitations associated with current therapies, such as autologous bone grafting. While many bone tissue engineering approaches have traditionally focused on synthetic materials (such as polymers or hydrogels), there has been a lot of excitement surrounding the use of natural materials due to their biologically inspired properties. Fibrin is a natural scaffold formed following tissue injury that initiates hemostasis and provides the initial matrix useful for cell adhesion, migration, proliferation, and differentiation. Fibrin has captured the interest of bone tissue engineers due to its excellent biocompatibility, controllable biodegradability, and ability to deliver cells and biomolecules. Fibrin is particularly appealing because its precursors, fibrinogen, and thrombin, which can be derived from the patient's own blood, enable the fabrication of completely autologous scaffolds. In this article, we highlight the unique properties of fibrin as a scaffolding material to treat bone defects. Moreover, we emphasize its role in bone tissue engineering nanocomposites where approaches further emulate the natural nanostructured features of bone when using fibrin and other nanomaterials. We also review the preparation methods of fibrin glue and then discuss a wide range of fibrin applications in bone tissue engineering. These include the delivery of cells and/or biomolecules to a defect site, distributing cells, and/or growth factors throughout other pre-formed scaffolds and enhancing the physical as well as biological properties of other biomaterials. Thoughts on the future direction of fibrin research for bone tissue engineering are also presented. In the future, the development of fibrin precursors as recombinant proteins will solve problems associated with using multiple or single-donor fibrin glue, and the combination of nanomaterials that allow for the incorporation of biomolecules with fibrin will significantly improve the efficacy of fibrin for numerous bone tissue engineering applications.

Self-Targeting, Immune Transparent Plasma Protein Coated Nanocomplex for Noninvasive Photothermal Anticancer Therapy

Cancer cells exhibit specific physiological differences compared to normal cells. Most surface membranes of cancer cells are characterized by high expression of given protein receptors, such as albumin, transferrin, and growth factors that are also present in the plasma of patients themselves, but are lacking on the surface of normal cells. These distinct features between cancer and normal cells can serve as a niche for developing specific treatment strategies. Near-infrared (NIR)-light-triggered therapy platforms are an interesting novel avenue for use in clinical nanomedicine. As a photothermal agent, conducting polymer nanoparticles, such as polypyrrole (PPy), of great NIR light photothermal effects and good biocompatibility, show promising applications in cancer treatments through the hyperthermia mechanism. Autologous plasma proteins coated PPy nanoparticles for hyperthermia therapy as a novel core technology platform to treat cancers through secreted protein acid and rich in cysteine targeting are developed here. This approach can provide unique features of specific targeting toward cancer cell surface markers and immune transparency to avoid recognition and attack by defense cells and achieve prolonged circulation half-life. This technology platform unveils new clinical options for treatment of cancer patients, supporting the emergence of innovative clinical products.

Wound healing: time to look for intelligent, 'natural' immunological approaches?

There is now good evidence that cytokines and growth factors are key factors in tissue repair and often exert anti-infective activities. However, engineering such factors for global use, even in the most remote places, is not realistic. Instead, we propose to examine how such factors work and to evaluate the reparative tools generously provided by 'nature.' We used two approaches to address these objectives. The first approach was to reappraise the internal capacity of the factors contributing the most to healing in the body, i.e., blood platelets. The second was to revisit natural agents such as whey proteins, (honey) bee venom and propolis. The platelet approach elucidates the inflammation spectrum from physiology to pathology, whereas milk and honey derivatives accelerate diabetic wound healing. Thus, this review aims at offering a fresh view of how wound healing can be addressed by natural means.

White cell and platelet content affects the release of bioactive factors in different blood-derived scaffolds

Platelet-derived factors are biomaterials that might accelerate healing process in oral, maxillofacial, and several other applications. Release of specific factors by platelet concentrates is critical to achieving a successful outcome. Here, we have shown that platelet-rich fibrin (PRF) clots were beneficial sources of leukocytes, which may directly affect the release of chemokines and growth factors. When compared with the standard leukocyte-PRF (L-PRF), the experimental low-force modified procedure [defined as advanced-PRF (A-PRF)] entrapped the same content of viable leukocytes, released a similar amount of inflammatory cytokines, but secreted 3-, 1.6-, 3-, and 1.2-fold higher levels of Eotaxin, CCL5, platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF), respectively. A leukocyte-free scaffold, such as plasma rich in growth factors (PRGF), released only platelet-specific factors and, in particular, the F3 fraction, the richest in growth factors, secreted higher amount of CCL5 and PDGF compared to F1 and F2 fractions. In conclusion, different procedures and leukocyte content affect cytokine, chemokines, and growth factor release from platelet derivatives, which may be helpful in different clinical settings.

Decrease of serum biomarker of type II Collagen degradation (Coll2-1) by intra-articular injection of an autologous plasma-rich-platelet in patients with unilateral primary knee osteoarthritis

OBJECTIVE

This study aimed to evaluate the effect of one dose of intra-articular injection of (PRP) in the knee joint on a specific osteoarthritis (OA) serum biomarker of cartilage degeneration, Collagen 2-1 (Coll2-1), over a short period of 3 months. The aim extended to clarify the effect of PRP on the functional status of the osteoarthritic knee joint.

MATERIAL AND METHODS

Sixty patients with primary unilateral knee OA were enrolled in this study. They were subdivided according to Kellgren-Lawrence grading scale (KL) into (Group I): including patients with KL grade < 3 and (Group II): including patients with KL grade ≥3. Patients were asked to complete the Western Ontario and McMaster Universities Arthritis Index (WOMAC) Score. PRP was prepared and injected immediately into the affected knee. Serum Coll2-1 (S.Coll2-1) concentration was measured by enzyme-linked immunosorbent assay (ELISA) kit pre and 3 months after PRP injection.

RESULTS

Significant reduction in S.Coll2-1 concentration in primary knee OA patients; (p<0.001) and (p<0.05) in group I and group II respectively as well as significant improvements in WOMAC total and WOMAC sub-scores values were noted after single intra-articular PRP injection with maximal functional improvements were achieved after 3 months (p<0.001). Mild cases experienced favorable results with no remarkable adverse reactions were observed.

CONCLUSION

Reduction in specific OA biomarker S.Coll2-1 following intra-articular PRP injection emphasize that PRP could be a promising safe and tolerable effective therapeutic option which improves function from basal states in primary knee OA patients.

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.

Use of autologous platelet-rich plasma for a delayed consolidation of a tibial fracture in a young donkey

A 9-month-old filly donkey was referred for a comminuted diaphyseal fracture of the right tibia. Surgical osteosynthesis, with multiple lag screws and a neutralization plate, was performed for anatomical reconstruction. Despite a good gait condition, delayed bone consolidation and a bone gap were evident on follow up radiographic evaluations. Due to delayed healing, autologous platelet-rich plasma (PRP) was injected on the surface of the tibia. Increased bone consolidation was evident on radiographs one month after the PRP injection. Progressive filling of both the fracture lines and bone gap continued during the six-month follow up. Clinical outcome was excellent. Autologous PRP should be considered as a practical adjuvant therapy in bone healing process in donkeys.

Feasibility of improving platelet-rich plasma therapy by using chitosan with high platelet activation ability

Platelet-rich plasma (PRP) is blood plasma containing a high number of platelets that release growth factors for wound healing and tissue regeneration. In the present study, the feasibility of improving PRP therapy by using chitosan that exhibits high platelet activation ability was investigated. A total of 13 chitosan samples with different molecular weight (Mw) and degree of deacetylation (DDA) were individually added to blood samples of rats and the amount of growth factors, albumin and fibrinogen in plasma was measured. To examine the influence of plasma activated by chitosan on the proliferation of fibroblasts and adipose tissue-derived stromal cells (ASCs), the plasma was added to the culture medium of human fibroblasts and adipose tissue-derived stromal cells. Chitosan with a DDA of >75% increased the release of platelet factor 4 into the plasma. The amount of growth factors released into the plasma and platelet activation varied depending on the Mw and DDA, while albumin and fibrinogen were hardly affected. The proliferation rate was highest when using plasma activated by chitosan with a DDA of 75-85% and an Mw of 50,000-190,000 Da. These results suggested that the effectiveness of PRP therapy may be improved by using chitosan with a DDA of 75-85% and an Mw of 50,000-190,000 Da.

Regenerative potential of leucocyte- and platelet-rich fibrin. Part A: intra-bony defects, furcation defects and periodontal plastic surgery. A systematic review and meta-analysis

AIM

To analyse the regenerative potential of leucocyte- and platelet-rich fibrin (L-PRF) during periodontal surgery.

MATERIALS AND METHODS

An electronic and hand search were conducted in three databases. Only randomized clinical trials were selected and no follow-up limitation was applied. Pocket depth (PD), clinical attachment level (CAL), bone fill, keratinized tissue width (KTW), recession reduction and root coverage (%) were considered as outcome. When possible, meta-analysis was performed.

RESULTS

Twenty-four articles fulfilled the inclusion and exclusion criteria. Three subgroups were created: intra-bony defects (IBDs), furcation defects and periodontal plastic surgery. Meta-analysis was performed in all the subgroups. Significant PD reduction (1.1 ± 0.5 mm, p < 0.001), CAL gain (1.2 ± 0.6 mm, p < 0.001) and bone fill (1.7 ± 0.7 mm, p < 0.001) were found when comparing L-PRF to open flap debridement (OFD) in IBDs. For furcation defects, significant PD reduction (1.9 ± 1.5 mm, p = 0.01), CAL gain (1.3 ± 0.4 mm, p < 0.001) and bone fill (1.5 ± 0.3 mm, p < 0.001) were reported when comparing L-PRF to OFD. When L-PRF was compared to a connective tissue graft, similar outcomes were recorded for PD reduction (0.2 ± 0.3 mm, p > 0.05), CAL gain (0.2 ± 0.5 mm, p > 0.05), KTW (0.3 ± 0.4 mm, p > 0.05) and recession reduction (0.2 ± 0.3 mm, p > 0.05).

CONCLUSIONS

L-PRF enhances periodontal wound healing.

Platelet-rich plasma: a case study for the identification of disinvestment opportunities using horizon scanning

Objective This paper discusses the potential for horizon scanning to identify low-value, inappropriate clinical practices that deliver minimal benefit to patients and represent a considerable financial burden on the health system. Methods Platelet-rich plasma (PRP) was identified by routine horizon scanning as a potentially innovative treatment alternative for osteoarthritis of the knee. A rapid, non-systematic assessment of the evidence pertaining to the safety and effectiveness of PRP compared with nonsteroidal anti-inflammatory drugs (NSAIDs) for the treatment of osteoarthritis of the knee was conducted. Results The evidence base supporting the use of PRP for the treatment of osteoarthritis was poor. No comparative studies were identified that compared the use of PRP to NSAIDs, the current treatment option for osteoarthritis of the knee in Australia. Despite the lack of effectiveness evidence, the use of PRP injections was rapidly increasing in the private sector using an inappropriate Medicare Benefits Schedule item number. Conclusions This assessment highlights the potential of using established horizon scanning methodologies to identify targets for full or partial disinvestment of ineffective, inefficient or harmful clinical practices. What is known about the topic? PRP is rapidly diffusing in the private health system in Australia, however the use of a Medicare Benefits Schedule item number meant that this practice was being subsidised by the public reimbursement of treatment fees. What does this paper add? Traditional horizon scanning tends to identify technologies for health systems to invest in. The evidence on the effectiveness of PRP was examined with the purpose of exploring investment in an innovative treatment that may have reduced the number of invasive procedures being performed in the public hospital system. The current evidence base does not support the use of PRP injections for the treatment of osteoarthritis. It does, however, support the use of horizon scanning as an inexpensive methodology to identify possible disinvestment targets associated with potential patient harm and high health service expenditure. What are the implications for practitioners? Practitioners should be aware that public funding for the injection of PRP should not be used for the treatment of osteoarthritis.

Efficacy of Autologous Platelet-rich Plasma Glue in Weight Loss Sequelae Surgery and Breast Reduction: A Prospective Study

Background:

Seroma and hematoma formations are the most common complications after plastic surgery. The aim of this study was to assess the efficacy of autologous platelet-rich plasma (A-PRP) glue to reduce postoperative wound complications and improve surgical outcomes.

Methods:

Fifty-four patients were included in this study. They underwent breast reduction surgery, abdominoplasty, or limb lifting with A-PRP glue application on the entire surface of the subcutaneous tissue at the time of suture. Retrospective data were used for the control group. The primary endpoint was the incidence of postoperative seroma or hematoma. The secondary endpoint was the Patient and Observer Scar Assessment Scale score.

Results:

Demographics and clinical characteristics were not statistically different between the A-PRP glue group and the control group regarding age, sex ratio, and body mass index. After abdominoplasty, 37.5% of patients (3/8) in the control group experienced seroma and hematoma complications versus 12.5% of patients (2/16) in the A-PRP glue group (P = 0.55 and P = 0.25, respectively). After limb lifting, 50% of patients experienced postoperative complications in the control group versus no patient in the A-PRP glue group (P = 0.03*; * indicates that the P value is significant). After breast reduction, no patient experienced complication in the A-PRP glue group versus 25% of patients in the control group who experienced hematoma (P = 0.04*). The scar quality assessed 12 months after surgery showed no statistical differences between the groups.

Conclusions:

A-PRP glue seems effective to prevent seroma formation after limb lifting and hematoma formation after breast reduction. Wound-healing quality did not seem to be improved.

Platelet-Rich Plasma Increases Growth and Motility of Adipose Tissue-Derived Mesenchymal Stem Cells and Controls Adipocyte Secretory Function

Adipose tissue‐derived mesenchymal stem cells (Ad‐MSC) and platelet derivatives have been used alone or in combination to achieve regeneration of injured tissues. We have tested the effect of platelet‐rich plasma (PRP) on Ad‐MSC and adipocyte function. PRP increased Ad‐MSC viability, proliferation rate and G1‐S cell cycle progression, by at least 7‐, 2‐, and 2.2‐fold, respectively, and reduced caspase 3 cleavage. Higher PRP concentrations or PRPs derived from individuals with higher platelet counts were more effective in increasing Ad‐MSC growth. PRP also accelerated cell migration by at least 1.5‐fold. However, PRP did not significantly affect mature adipocyte viability, differentiation and expression levels of PPAR‐γ and AP‐2 mRNAs, while it increased leptin production by 3.5‐fold. Interestingly, PRP treatment of mature adipocytes also enhanced the release of Interleukin (IL)‐6, IL‐8, IL‐10, Interferon‐γ, and Vascular Endothelial Growth Factor. Thus, data are consistent with a stimulatory effect of platelet derivatives on Ad‐MSC growth and motility. Moreover, PRP did not reduce mature adipocyte survival and increased the release of pro‐angiogenic factors, which may facilitate tissue regeneration processes. © 2015 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc. J. Cell. Biochem. 116: 2408–2418, 2015. © 2015 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc.

Graphene Oxide promotes embryonic stem cell differentiation to haematopoietic lineage

Pluripotent stem cells represent a promising source of differentiated tissue-specific stem and multipotent progenitor cells for regenerative medicine and drug testing. The realisation of this potential relies on the establishment of robust and reproducible protocols of differentiation. Several reports have highlighted the importance of biomaterials in assisting directed differentiation. Graphene oxide (GO) is a novel material that has attracted increasing interest in the field of biomedicine. In this study, we demonstrate that GO coated substrates significantly enhance the differentiation of mouse embryonic stem (ES) cells to both primitive and definitive haematopoietic cells. GO does not affect cell proliferation or survival of differentiated cells but rather enhances the transition of haemangioblasts to haemogenic endothelial cells, a key step during haematopoietic specification. Importantly, GO also improves, in addition to murine, human ES cell differentiation to blood cells. Taken together, our study reveals a positive role for GO in haematopoietic differentiation and suggests that further functionalization of GO could represent a valid strategy for the generation of large numbers of functional blood cells. Producing these cells would accelerate haematopoietic drug toxicity testing and treatment of patients with blood disorders or malignancies.

Smart blood cell and microvesicle-based Trojan horse drug delivery: Merging expertise in blood transfusion and biomedical engineering in the field of nanomedicine

Therapeutic and diagnostic applications of nanomedicine are playing increasingly important roles in human health. Various types of synthetic nanoparticles, including liposomes, micelles, and other nanotherapeutic platforms and conjugates, are being engineered to encapsulate or carry drugs for treating diseases such as cancer, cardiovascular disorders, neurodegeneration, and inflammations. Nanocarriers are designed to increase the half-life of drugs, decrease their toxicity and, ideally, target pathological sites. Developing smart carriers with the capacity to deliver drugs specifically to the microenvironment of diseased cells with minimum systemic toxicity is the goal. Blood cells, and potentially also the liposome-like micro- and nano-vesicles they generate, may be regarded as ideally suited to perform such specific targeting with minimum immunogenic risks. Blood cell membranes are "decorated" with complex physiological receptors capable of targeting and communicating with other cells and tissues and delivering their content to the surrounding pathological microenvironment. Blood cells, such as erythrocytes, have been developed as permeable carriers to release drugs to diseased tissues or act as biofactory allowing enzymatic degradation of a pathological substrate. Interestingly, attempts are also being made to improve the targeting capacity of synthetic nanoparticles by "decorating" their surface with blood cell membrane receptor-like biochemical structures. Research is needed to further explore the benefits that blood cell-derived microvesicles, as a Trojan horse delivery systems, can bring to the arsenal of therapeutic micro- and nanotechnologies. This short review focuses on the therapeutic roles that red blood cells and platelets can play as smart drug-delivery systems, and highlights the benefits that blood transfusion expertise can bring to this exciting and novel biomedical engineering field.

Red blood cell ghosts as promising drug carriers to target wound infections

Autologous red blood cell ghosts (RBC ghosts) can carry cytokines to the sites of inflammation. The targeting moiety of the RBC ghosts is associated with the nature of purulent inflammation, where the erythrocytes are phagocyted and encapsulated drugs are released. In the present study we have investigated the healing potential of RBC ghosts loaded with cytokine IL-1β and antibiotic. Additionally, the pharmacokinetic properties of RBC ghosts loaded with IL-1β were studied. 35 Male Wistar rats (250-300g) were used in the pharmacokinetic study and in a wound infection model where a suspension of Staphylococcus aureus was placed into a surgical cut of the skin and subcutaneous tissue in the femoral region. In order to monitor progression of the wound repair processes, wound swabs or aspiration biopsies were taken for analyses on the 1st-6th days. Wound repair dynamics assessment was based on suppression of S. aureus growth, signs of pain, time of disappearance of pus and infiltration around the wound. Visual observations, as well as microbiological and cytological analysis of wound exudates demonstrated a significant acceleration of healing processes in a group of animals treated with a local injection of IL-1β and ceftriaxone encapsulated into RBC ghosts when compared to the animals treated either with a local or IM injection of free drugs. For the pharmacokinetic study, single IV injections of either free or encapsulated IL-1β were made and the concentration of IL-1β in serum samples and tissue homogenates were determined. Encapsulation in RBC ghosts improved pharmacokinetic profiles of IL-1β by increasing the half-life, reducing its clearance, and increasing the deposition of the drug in the liver, spleen and lungs. These data suggest that RBC ghosts are effective drug carriers for targeted delivery of cytokines to the sites of inflammation, and have a potential for improving the treatment outcomes of purulent diseases.

Mesenchymal Stem Cells in Chronic Wounds: The Spectrum from Basic to Advanced Therapy

Significance: Almost 7 million Americans have chronic cutaneous wounds and billions of dollars are spent on their treatment. The number of patients with nonhealing wounds keeps increasing worldwide due to an ever-aging population, increasing number of obese and diabetic patients, and cardiovascular disease. Recent Advances: Advanced treatments for difficult wounds are needed. Therapy with mesenchymal stem cells (MSCs) is attractive due to their differentiating potential, their immunomodulating properties, and their paracrine effects. Critical Issues: New technologies (including growth factors and skin substitutes) are now widely used for stimulating wound healing. However, in spite of these advances, the percentage of complete wound closure in most clinical situations is around 50-60%. Moreover, there is a high rate of wound recurrence. Future Directions: Recently, it has been demonstrated that MSCs speed up wound healing by decreasing inflammation, by promoting angiogenesis, and by decreasing scarring. However, there are some potential limitations to successful MSC therapy. These limitations include the need to improve cell delivery methods, cell viability, heterogeneity in MSC preparations, and suboptimal wound bed preparation. Further large, controlled clinical trials are needed to establish the safety of MSCs before widespread clinical application.

The phagocytic fitness of leucopatches may impact the healing of chronic wounds

Chronic non-healing wounds are significantly bothersome to patients and can result in severe complications. In addition, they are increasing in numbers, and a challenging problem to the health-care system. Handling of chronic, non-healing wounds can be discouraging due to lack of improvement, and a recent explanation can be the involvement of biofilm infections in the pathogenesis of non-healing wounds. Therefore, new treatment alternatives to improve outcome are continuously sought-after. Autologous leucopatches are such a new, adjunctive treatment option, showing promising clinical effects. However, the beneficial effect of the patches are not understood fully, although a major contribution is believed to be from the release of stimulating growth factors from activated thrombocytes within the leucopatch. Because the leucopatches also contain substantial numbers of leucocytes, the aim of the present study was to investigate the activity of the polymorphonuclear neutrophils (PMNs) within the leucopatch. By means of burst assay, phagocytosis assay, migration assay, biofilm killing assay and fluorescence in-situ hybridization (FISH) assay we showed significant respiratory burst in PMNs, active phagocytosis and killing of Pseudomonas aeruginosa by the leucopatch. In addition, bacterial-induced migration of PMNs from the leucopatch was shown, as well as uptake of P. aeruginosa by PMNs within the leucopatch. The present study substantiated that at least part of the beneficial clinical effect in chronic wounds by leucopatches is attributed to the activity of the PMNs in the leucopatch.

Advancing biomaterials of human origin for tissue engineering

Biomaterials have played an increasingly prominent role in the success of biomedical devices and in the development of tissue engineering, which seeks to unlock the regenerative potential innate to human tissues/organs in a state of deterioration and to restore or reestablish normal bodily function. Advances in our understanding of regenerative biomaterials and their roles in new tissue formation can potentially open a new frontier in the fast-growing field of regenerative medicine. Taking inspiration from the role and multi-component construction of native extracellular matrices (ECMs) for cell accommodation, the synthetic biomaterials produced today routinely incorporate biologically active components to define an artificial in vivo milieu with complex and dynamic interactions that foster and regulate stem cells, similar to the events occurring in a natural cellular microenvironment. The range and degree of biomaterial sophistication have also dramatically increased as more knowledge has accumulated through materials science, matrix biology and tissue engineering. However, achieving clinical translation and commercial success requires regenerative biomaterials to be not only efficacious and safe but also cost-effective and convenient for use and production. Utilizing biomaterials of human origin as building blocks for therapeutic purposes has provided a facilitated approach that closely mimics the critical aspects of natural tissue with regard to its physical and chemical properties for the orchestration of wound healing and tissue regeneration. In addition to directly using tissue transfers and transplants for repair, new applications of human-derived biomaterials are now focusing on the use of naturally occurring biomacromolecules, decellularized ECM scaffolds and autologous preparations rich in growth factors/non-expanded stem cells to either target acceleration/magnification of the body's own repair capacity or use nature's paradigms to create new tissues for restoration. In particular, there is increasing interest in separating ECMs into simplified functional domains and/or biopolymeric assemblies so that these components/constituents can be discretely exploited and manipulated for the production of bioscaffolds and new biomimetic biomaterials. Here, following an overview of tissue auto-/allo-transplantation, we discuss the recent trends and advances as well as the challenges and future directions in the evolution and application of human-derived biomaterials for reconstructive surgery and tissue engineering. In particular, we focus on an exploration of the structural, mechanical, biochemical and biological information present in native human tissue for bioengineering applications and to provide inspiration for the design of future biomaterials.

Human platelet lysate: Replacing fetal bovine serum as a gold standard for human cell propagation?

The essential physiological role of platelets in wound healing and tissue repair builds the rationale for the use of human platelet derivatives in regenerative medicine. Abundant growth factors and cytokines stored in platelet granules can be naturally released by thrombin activation and clotting or artificially by freeze/thaw-mediated platelet lysis, sonication or chemical treatment. Human platelet lysate prepared by the various release strategies has been established as a suitable alternative to fetal bovine serum as culture medium supplement, enabling efficient propagation of human cells under animal serum-free conditions for a multiplicity of applications in advanced somatic cell therapy and tissue engineering. The rapidly increasing number of studies using platelet derived products for inducing human cell proliferation and differentiation has also uncovered a considerable variability of human platelet lysate preparations which limits comparability of results. The main variations discussed herein encompass aspects of donor selection, preparation of the starting material, the possibility for pooling in plasma or additive solution, the implementation of pathogen inactivation and consideration of ABO blood groups, all of which can influence applicability. This review outlines the current knowledge about human platelet lysate as a powerful additive for human cell propagation and highlights its role as a prevailing supplement for human cell culture capable to replace animal serum in a growing spectrum of applications.

The influence of platelet-derived products on angiogenesis and tissue repair: a concise update

Platelet degranulation allows the release of a large amount of soluble mediators, is an essential step for wound healing initiation, and stimulates clotting, and angiogenesis. The latter process is one of the most critical biological events observed during tissue repair, increasing the growth of blood vessels in the maturing wound. Angiogenesis requires the action of a variety of growth factors that act in an appropriate physiological ratio to assure functional blood vessel restoration. Platelets release main regulators of angiogenesis: Vascular Endothelial Growth Factors (VEGFs), basic fibroblast growth factor (FGF-2), and Platelet derived growth factors (PDGFs), among others. In order to stimulate tissue repair, platelet derived fractions have been used as an autologous source of growth factors and biomolecules, namely Platelet Rich Plasma (PRP), Platelet Poor Plasma (PPP), and Platelet Rich Fibrin (PRF). The continuous release of these growth factors has been proposed to promote angiogenesis both in vitro and in vivo. Considering the existence of clinical trials currently evaluating the efficacy of autologous PRP, the present review analyses fundamental questions regarding the putative role of platelet derived fractions as regulators of angiogenesis and evaluates the possible clinical implications of these formulations.

A Current View of Functional Biomaterials for Wound Care, Molecular and Cellular Therapies

The intricate process of wound healing involves activation of biological pathways that work in concert to regenerate a tissue microenvironment consisting of cells and external cellular matrix (ECM) with enzymes, cytokines, and growth factors. Distinct stages characterize the mammalian response to tissue injury: hemostasis, inflammation, new tissue formation, and tissue remodeling. Hemostasis and inflammation start right after the injury, while the formation of new tissue, along with migration and proliferation of cells within the wound site, occurs during the first week to ten days after the injury. In this review paper, we discuss approaches in tissue engineering and regenerative medicine to address each of these processes through the application of biomaterials, either as support to the native microenvironment or as delivery vehicles for functional hemostatic, antibacterial, or anti-inflammatory agents. Molecular therapies are also discussed with particular attention to drug delivery methods and gene therapies. Finally, cellular treatments are reviewed, and an outlook on the future of drug delivery and wound care biomaterials is provided.

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.

Platelet-rich plasma in orthopedic therapy: a comparative systematic review of clinical and experimental data in equine and human musculoskeletal lesions

BACKGROUND

This systematic review aimed to present and critically appraise the available information on the efficacy of platelet rich plasma (PRP) in equine and human orthopedic therapeutics and to verify the influence of study design and methodology on the assumption of PRP's efficacy. We searched Medline, PubMed, Embase, Bireme and Google Scholar without restrictions until July 2013. Randomized trials, human cohort clinical studies or case series with a control group on the use of PRP in tendons, ligaments or articular lesions were included. Equine clinical studies on the same topics were included independently of their design. Experimental studies relevant to the clarification of PRP's effects and mechanisms of action in tissues of interest, conducted in any animal species, were selected.

RESULTS

This review included 123 studies. PRP's beneficial effects were observed in 46.7% of the clinical studies, while the absence of positive effects was observed in 43.3%. Among experimental studies, 73% yielded positive results, and 7.9% yielded negative results. The most frequent flaws in the clinical trials' designs were the lack of a true placebo group, poor product characterization, insufficient blinding, small sampling, short follow-up periods, and adoption of poor outcome measures. The methods employed for PRP preparation and administration and the selected outcome measures varied greatly. Poor study design was a common feature of equine clinical trials. From studies in which PRP had beneficial effects, 67.8% had an overall high risk of bias. From the studies in which PRP failed to exhibit beneficial effects, 67.8% had an overall low risk of bias.

CONCLUSIONS

Most experimental studies revealed positive effects of PRP. Although the majority of equine clinical studies yielded positive results, the human clinical trials' results failed to corroborate these findings. In both species, beneficial results were more frequently observed in studies with a high risk of bias. The use of PRP in musculoskeletal lesions, although safe and promising, has still not shown strong evidence in clinical scenarios.

Safety assessment of bone marrow derived MSC grown in platelet-rich plasma

The injection of endothelial progenitor cells and mononuclear cells derived from bone marrow at the ischemic region of peripheral artery disease patients is reported to be effective for therapeutic angiogenesis; however, these cell therapies require large amounts of bone marrow to obtain sufficient numbers of cells. To solve this problem, we attempted to culture bone-marrow-derived mesenchymal stem cells (BM-MSC), which are supposed to secrete several cytokines that promote angiogenesis. We also focused on using platelet-rich plasma (PRP) as a supplement for cell culture instead of fetal bovine serum. Human BM-MSC obtained from healthy volunteers expanded rapidly when cultured with 10% PRP prepared from their own blood. FACS analysis revealed that these cultured human MSC were homogeneous populations, and chromosomal analysis showed a normal karyotype. Moreover, the angiogenetic effect was apparent two weeks after human BM-MSC were injected into the ischemic muscle in SCID mice. Tumor formation was not detected three months after injection into SCID mice either subcutaneously or intramuscularly. To simulate clinical settings, canine BM-MSC were grown with canine PRP and injected into their ischemic muscles. We confirmed that donor cells existed in situ two and six weeks after operation without any side effects. These results suggest that cultured human BM-MSC can be a promising cell source for therapeutic angiogenesis.

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Human bone marrow-derived mesenchymal stem cells cultured with own platelet rich plasma.

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The angiogenetic effect of cultured human BM-MSC.

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Safety evaluation of cultured human BM-MSC.

New frontiers for platelet CD154

The role of platelets extends beyond hemostasis. The pivotal role of platelets in inflammation has shed new light on the natural history of conditions associated with acute or chronic inflammation. Beyond the preservation of vascular integrity, platelets are essential to tissue homeostasis and platelet-derived products are already used in the clinics. Unanticipated was the role of platelets in the adaptative immune response, allowing a renewed conceptual approach of auto-immune diseases. Platelets are also important players in cancer growth and dissemination. Platelets fulfill most of their functions through the expression of still incompletely characterized membrane-bound or soluble mediators. Among them, CD154 holds a peculiar position, as platelets represent a major source of CD154 and as CD154 contributes to most of these new platelet attributes. Here, we provide an overview of some of the new frontiers that the study of platelet CD154 is opening, in inflammation, tissue homeostasis, immune response, hematopoiesis and cancer.

Platelet derivatives in regenerative medicine: an update

Prior preclinical and clinical studies support the use of platelet-derived products for the treatment of soft and hard tissue lesions. These regenerative effects are controlled by autocrine and paracrine biomolecules including growth factors and cytokines contained in platelet alpha granules. Each growth factor is involved in a phase of the healing process, such as inflammation, collagen synthesis, tissue granulation, and angiogenesis collectively promoting tissue restitution. Platelet derivatives have been prepared as platelet-rich plasma, platelet gel, platelet-rich fibrin, and platelet eye drops. These products vary in their structure, growth factors, composition, and cytokine concentrations. Here, we review the current use of platelet-derived biological products focusing on the rationale for their use and the main requirements for their preparation. Variation in the apparent therapeutic efficacy may have resulted from a lack of reproducible, standardized protocols for preparation. Despite several individual studies showing favorable treatment effects, some randomized controlled trials as well as meta-analyses have found no constant clinical benefit from the application of platelet-derived products for prevention of tissue lesions. Recently, 3 published studies in dentistry showed an improvement in bone density. Seven published studies showed positive results in joint regeneration. Five published studies demonstrated an improvement in the wound healing, and an improvement of eye epithelial healing was observed in 2 reports. Currently, at least 14 ongoing clinical trials in phase 3 or 4 have been designed with large groups of treated patients (n > 100). Because the rationale of the therapy with platelet-derived compounds is still debated, a definitive insight can be acquired only when these large randomized trials will be completed.

Multifaceted regenerative lives of expired platelets in the second decade of the 21st century

A traditional concept in transfusion medicine is the expiration of platelet concentrates 5-7 days after collection due to storage conditions that favor the risks of bacterial contamination and may lead to a gradual alteration of platelet hemostatic power. Newer findings are strongly suggesting that, after their supposed expiration date, platelet concentrates still contain multiple functional growth factors and cytokines and actually have unaltered power for application in regenerative medicine and cell therapy. Expired platelets can be a valuable source of growth factors to promote the healing of wounds, and can be used for ex vivo expansion of stem cells. There is also preliminary evidence that infusible platelet membrane (IPM) from outdated platelet concentrates and thrombosomes have potential clinical applications as hemostatic products. Experimental work is certainly needed to further validate and standardize the clinical potential of "expired" platelet blood products in human clinical medicine. However, strong evidence accumulates toward a potential for further manufacturing avenues of expired platelet concentrates into valuable therapeutic and clinically relevant products.

Expired and Pathogen-Inactivated Platelet Concentrates Support Differentiation and Immunomodulation of Mesenchymal Stromal Cells in Culture

Platelet lysates have been reported as suitable cell culture supplement for cultures of mesenchymal stromal cells (MSCs). The demand for safe and animal-free cultures of MSCs is linked to the potential application of MSCs in clinics. While the use of platelet lysates offers an alternative to animal serum in MSC cultures, obtaining supplies of fresh platelet concentrates for lysate production is challenging and raises concerns due to the already existing shortage of platelet donors. We have previously demonstrated that expired platelet concentrates may represent a good source of platelets for lysate production without competing with blood banks for platelet donors. The INTERCEPT Blood System™ treatment of platelet concentrates allows for prolonged storage up to 7 days, using highly specific technology based on amotosalen and UV-A light. The INTERCEPT system has therefore been implemented in blood processing facilities worldwide. In this study, we evaluated the suitability of INTERCEPT-treated, expired platelet concentrates, processed into platelet lysates, for the culture of MSCs compared to nontreated expired platelets. Bone marrow-derived MSCs were cultured in media supplemented with either platelet lysates from traditionally prepared expired platelet concentrates or in platelet lysates from expired and pathogen-inactivated platelet concentrates. The effects of pathogen inactivation on the ability of the platelets to support MSCs in culture were determined by evaluating MSC immunomodulation, immunophenotype, proliferation, and trilineage differentiation. Platelet lysates prepared from expired and pathogen-inactivated platelet concentrates supported MSC differentiation and immunosuppression better compared to traditionally prepared platelet lysates from expired platelet units. Pathogen inactivation of platelets with the INTERCEPT system prior to use in MSC culture had no negative effects on MSC immunophenotype or proliferation. In conclusion, the use of expired pathogen-inactivated platelet units from blood banks to prepare platelet lysates for the culture of MSCs is desirable and attainable.

Improvement in the repair of defects in maxillofacial soft tissue in irradiated minipigs by a mixture of adipose-derived stem cells and platelet-rich fibrin

To find out if adipose-derived stem cells (ASC) and platelet-rich fibrin (PRF), alone or combined, had any effect on the repair of maxillofacial soft tissue defects in irradiated minipigs, ASC were isolated, characterised, and expanded. Twenty female minipigs, the right parotid glands of which had been irradiated, were randomly divided into 4 groups of 5 each: those in the first group were injected with both ASC and PRF (combined group), the second group was injected with ASC alone (ASC group), the third group with PRF alone (PRF group), and the fourth group with phosphate buffer saline (PBS) (control group). Six months after the last injection, the size and depth of each defect were assessed, and subcutaneous tissues were harvested, stained with haematoxylin and eosin, and examined immunohistologically and for apoptosis. Expanded cells were successfully isolated and identified. Six months after injection the defects in the 3 treated groups were significantly smaller (p<0.001) and shallower (p<0.001) than those in the control group. Those in the combined group were the smallest and shallowest. Haematoxylin and eosin showed that the 3 treated groups contained more subcutaneous adipose tissue than the control group, and also had significantly greater vascular density (p<0.001) and fewer apoptotic cells (p<0.001). Both ASC and PRF facilitate the repair of defects in maxillofacial soft tissue in irradiated minipigs, and their combined use is more effective than their use as single agents.