Treatment of recalcitrant ulcers with allogeneic platelet gel from pooled platelets in aged hypomobile patients

Treatment of severe pressure ulcers with protein-enriched filtered platelet-rich plasma (PEFPRP): a possible management

Background: Biological dressings with non-transfusion blood components are among the treatments available for pressure ulcers (PUs). Biological dressings contain active concentrated pro-regenerative molecules that can modify and switch off local inflammatory pathways. This re-establishes the physiological homing, which results in healing. In our study, we used a biological component obtained by ultrafiltration of plasma-platelet concentrate: protein-enriched filtered platelet-rich plasma (PEFPRP) with a higher platelet and higher plasma protein concentration. We tested whether treatment with PEFPRP could improve healing in advanced-stage pressure ulcers with a large surface area. All the patients in this study had a surgical indication but were not able to undergo surgery for various reasons. Materials and methods: Ten patients with severe neurological disability and advanced-stage sacral pressure ulcers were treated with allogenic PEFPRP. The mean lesion surface area at T0 was 13.4 cm2 ( ± 9.8 SD). PEFPRP was derived from allogenic plasma-platelet apheresis that had been pre-ultrafiltered with a ProSmart™ filter (Medica, Italy) to obtain a concentration after filtration of the plasma protein (12-16 g/dL) and platelet (1-1.2 x 106 microL). Results and Conclusion: All cases showed a reduction in the surface area of the pressure ulcer and in the Pressure Ulcer Scale for Healing (PUSH) score. The mean reduction values at week 6 were as follows: -52% for surface area and -21% for PUSH. Rapid wound healing is fundamental to avoid infections and improve patients' quality of life. This blood component builds new tissue by creating a new extracellular matrix. This, in turn, promotes rapid restoration of the three-dimensional structure of the tissue necessary for healing deeper wounds. PEFPRP shrinks the PU and improves its morphological features (reducing undermining and boosting granulation tissue). PEFPRP also promotes tissue restoration, obtaining an optimal scar. It is a safe and feasible treatment, and these preliminary results support the use of PEFPRP in the treatment of pressure ulcers. PEFPRP dressings could be integrated in the standard treatment of advanced-stage PU.

Efficacy of allogeneic platelet growth factors in actinic cystitis: The resolution of trouble?

BACKGROUND

Actinic cystitis is a severe complication after radiotherapy for prostate cancer. It is a chronic inflammatory process that leads to an alteration of bladder mucosa with formation of petechiae and subsequently hematuria. Actinic cystitis responds poorly to medical treatment, with a heavy burden on patients' quality of life. Patients with refractory hematuria may undergo cystectomy in the attempt to control bleeding. We conducted a prospective study to evaluate the effectiveness of the allogeneic platelet growth factors for actinic cystitis.

METHODS AND MATERIAL

Nine patients with actinic cystitis were enrolled in this study. The primary outcome measures were the effects of the platelet growth factors on the injury of the bladder mucosa. The secondary outcome was the change in quality of life RESULTS: A total of 9 patients, mean age 68 (range 59-81) underwent a therapeutic program of bladder instillation with allogeneic platelets growth factors for 3 months. Of the 9 patients, all (100 %) had complete resolution of hematuria and urinary symptoms. After three months cystoscopy showed regeneration of the normal bladder mucosa. Biopsies allowed histological confirmation of the finding.

DISCUSSION

The instillation of allogeneic platelet growth factors in actinic cystitis is a new treatment that in this setting of patients appears promising in promoting a resolution of urinary symptoms, hematuria and avoiding a disabling surgery such as cystectomy.

Progress in Regenerative Medicine: Exploring Autologous Platelet Concentrates and Their Clinical Applications

The goal of regenerative medicine is to achieve tissue regeneration. In the past, commonly used techniques included autologous or allogeneic transplantation and stem cell therapy, which have limitations, such as a lack of donor sites in the case of autologous transplantation and the invasiveness of stem cell harvesting. In recent years, research has, therefore, focused on new and less invasive strategies to achieve tissue regeneration. A step forward in this direction has been made with the development of autologous platelet concentrates (APCs), which are derived from the patient's own blood. They can be classified into three generations: platelet-rich plasma (PRP), platelet-rich fibrin (PRF), and concentrated growth factors (CGFs). These APCs have different structural characteristics, depending on the distinctive preparation method, and contain platelets, leukocytes, and multiple growth factors, including those most involved in regenerative processes. The purpose of this review is to clarify the most used techniques in the field of regenerative medicine in recent years, comparing the different types of APCs and analyzing the preparation protocols, the composition of the growth factors, the level of characterization achieved, and their clinical applications to date.

Innovative Cell and Platelet Rich Plasma Therapies for Diabetic Foot Ulcer Treatment: The Allogeneic Approach

Cutaneous chronic wounds are a major global health burden in continuous growth, because of population aging and the higher incidence of chronic diseases, such as diabetes. Different treatments have been proposed: biological, surgical, and physical. However, most of these treatments are palliative and none of them can be considered fully satisfactory. During a spontaneous wound healing, endogenous regeneration mechanisms and resident cell activity are triggered by the released platelet content. Activated stem and progenitor cells are key factors for ulcer healing, and they can be either recruited to the wound site from the tissue itself (resident cells) or from elsewhere. Transplant of skin substitutes, and of stem cells derived from tissues such as bone marrow or adipose tissue, together with platelet-rich plasma (PRP) treatments have been proposed as therapeutic options, and they represent the today most promising tools to promote ulcer healing in diabetes. Although stem cells can directly participate to skin repair, they primarily contribute to the tissue remodeling by releasing biomolecules and microvesicles able to stimulate the endogenous regeneration mechanisms. Stem cells and PRP can be obtained from patients as autologous preparations. However, in the diabetic condition, poor cell number, reduced cell activity or impaired PRP efficacy may limit their use. Administration of allogeneic preparations from healthy and/or younger donors is regarded with increasing interest to overcome such limitation. This review summarizes the results obtained when these innovative treatments were adopted in preclinical animal models of diabetes and in diabetic patients, with a focus on allogeneic preparations.

A platelet-derived hydrogel improves neovascularisation in full thickness wounds

Platelets are a reservoir of growth factors, cytokines and chemokines involved in spontaneous wound repair. In this study, a platelet-rich and fibrin-rich hydrogel was generated from expired platelet components that would have otherwise been transfused. The material contained physiological concentrations of transforming growth factor β1 (TGF-β1, platelet-derived growth factor AB (PDGF-AB), PDGF-BB, insulin-like growth factor-1 (IGF-1), fibroblast growth factor 2 (FGF-2), and epidermal growth factor (EGF). The effect of the hydrogel on wound repair was investigated in SKH-1 mice. Full thickness dorsal wounds were created on the mice and treated with the hydrogel at various concentrations. Immunohistochemical staining with CD31 (endothelial cell marker) revealed that wounds treated with the hydrogel showed significantly enhanced vascularisation in the wound bed. Moreover, high levels of interleukin-6 (IL-6) and KC (IL-8 functional homologue) in treated wounds were sustained over a longer period of time, compared to untreated wounds. We postulate that sustained IL-6 is a driver, at least partly, of enhanced vascularisation in full thickness wounds treated with the hydrogel. Future work is needed to explore whether this hydrogel can be utilised as a treatment option when vascularisation is a critical limitation. STATEMENT OF SIGNIFICANCE: The economic cost of wound repair is estimated in billions of dollars each year. In many cases time required to vascularise wounds is a major contributor to slow wound repair. In this study, we developed a blood-derived platelet- and fibrin-rich hydrogel. It contains a number of growth factors actively involved in spontaneous wound healing. This hydrogel significantly improved dermal repair and vascularisation in a full-thickness wound mouse model. This study provides an action mechanism for modulation of localised inflammation.

Current applications of platelet gels in wound healing-A review

Human platelets play important roles in several physiologic and pathologic processes. Platelet concentrates are activated with thrombin or calcium, resulting in a viscous coagulum (platelet gel [PG]), composed of 95% platelets at least. PG is increasingly used for the treatment of a variety of soft and hard tissue defects, most notably in the management of chronic non-healing wounds. During wound healing, platelets not only play a critical role in primary hemostasis and thrombosis, but also release growth factors and cytokines to promote tissue regeneration, enhance collagen synthesis, and trigger an immune response. This review addresses a variety of aspects relevant to the functions of well-known platelet growth factors, animal and clinical studies of PG in the last decade, and different sources of platelets for PG. PG is used for non-healing chronic wounds, such as oral ulcerations related to epidermolysis bullosa and chronic graft-versus-host disease, for those, the traditional treatment effect is poor. PG maybe provide a new therapeutic direction for these diseases. Nevertheless, some uncertainty is present, the number of clinical studies is not enough. Hence, randomized controlled trials are still required to study the potential of the use of PG in the near future.

Allogeneic Platelet-Rich Plasma: Is It Safe and Effective for Wound Repair?

BACKGROUND

Platelet-rich plasma (PRP) and its derivatives are an emerging biotechnology whereby concentrated platelets provide damaged tissue with growth factors, cytokines, and other mediators to improve healing outcomes. Although there is strong evidence in the benefits of autologous PRP for both acute and chronic wounds, allogeneic PRP has been studied far less in comparison.

SUMMARY

In this mini-review, we discuss critical steps of allogenic PRP (and its derivatives) preparation. We performed a non-systematic review of the literature to identify animal and human subject studies testing allogenic PRP for wound treatment. We searched OVID Medline and PubMed for articles using the keywords "wound, ulcer, lesion, skin, and cutaneous" and "PRP, or platelet-rich plasma, or platelet-rich fibrin, or PRF, or platelet releasate" and "homologous, allogeneic or allogenic," which were limited to non-review articles and English language. Two studies in animal models and 8 studies in patients were reviewed. There were inconsistencies in preparation methods, treatment regimens, and some lacked a control group in their studies. Despite these variations, none of the studies identified any major side effects or adverse events. The treatment resulted in a reduced time to heal and/or reduced wound size in most cases. Key Messages: In situations where autologous PRP is not available or suitable, allogeneic PRP appears to provide a safe alternative. Its efficacy, however, requires larger-scale studies with appropriate controls. Standardization in PRP preparation and treatment regime are also needed to be able to interpret allogenic PRP efficacy.

Rheological Properties and Growth Factors Content of Platelet-Rich Plasma: Relevance in Veterinary Biomedical Treatments

Platelet-rich plasma (PRP) is a nontransfusional hemocomponent, considered as a powerful concentrate of growth factors (GFs) therapeutically used to stimulate tissue regeneration. The use of autologous PRP, as the patient’s own biological material, for therapeutic purposes represents a safe and effective alternative to conventional treatments in both human and veterinary medicine. The aim of this study was the characterization of canine PRP from rheological and biological points of view. Thus, a characterization of the viscoelastic properties of the PRP systems was performed in order to clarify the influence of different calcium concentrations, in the presence of autologous thrombin-rich solution, on the PRP gels’ mechanical properties, from which the applicability of these systems in biomedical treatments is strongly dependent. Then, an evaluation of the content of GFs in PRP, activated or not with thrombin, and stored at different temperatures (37 °C and −20 °C) was performed over time, outlining, for the first time, the importance of the effect of physiological temperature (37 °C) on the production of GFs. A clinical case study conducted in a dog with a complete rupture of the common calcaneal tendon (Achilles tendon) confirmed the relevance of this hemocomponent in the daily veterinary clinical activity and the potential translational value for human health.

Cord blood-derived platelet concentrates as starting material for new therapeutic blood components prepared in a public cord blood bank: from product development to clinical application

BACKGROUND

There are many advantages to using cord blood (CB) as a source of therapeutic platelet and plasma derivatives for regenerative medicine. These include availability, universal use, young donor source, and virally safe biological material, rich in tissue regenerative factors.

MATERIALS AND METHODS

We aimed to validate a bioprocess design for the production of cord blood-derived platelet concentrates (CBPC) in a public Cord Blood Bank (CBB). CBPC was defined as a product of 10±5 mL, 1,000±200×10⁹/L total platelets, free of erythrocytes and leukocytes. A total of 300 CB units were centrifuged in two steps to enrich for platelets, in compliance with Good Manufacturing Practice. The samples were tested for the degree of platelet activation present, and the levels of growth factor were analysed to evaluate their potential function. CBPC were then activated after thawing with 10% calcium gluconate to generate platelet gels (CBPG) to treat patients with diabetic foot ulcers.

RESULTS

After processing, 84% of the products fulfilled the acceptance criteria. Final products contained 1,017±149×10⁶ platelets/mL in 10±3mL of plasma. Platelet recovery was 50±9%. The methods described here ensure depletion of white and red blood cells down to a residual concentration of 0.2±0.1×10⁶/mL and 0.03±0.02×10⁶/mL, respectively. Platelets showed low levels of activation during processing, but were significantly activated after thawing, as indicated by an increase in CD62p expression. The growth factors EGF, VEGF, bFGF, PDGF AB/BB and TGF-β1 were at concentrations of 1,706±123 pg/mL; 1,602±227 pg/mL; 314±26 pg/mL; 30±1.5 ng/mL; 24±2 ng/mL (mean±standard error of mean), respectively. For clinical evaluation, a total of 21 CBPG were applied in 3 patients, with no reported adverse events and improvement of ulcers in all of them.

DISCUSSION

We designed and validated a highly reproducible, closed system method to manufacture high quality CBPC suitable for clinical applications using CB units not suitable for transplantation in a public CBB.

Effects of fibrin glue as a three-dimensional scaffold in cultivated adult human retinal pigment epithelial cells

This study was conducted to examine morphological, genotypic, and phenotypic alterations occurring in cultured adult human retinal pigment epithelial cells when encapsulated with different concentrations of fibrin glue. Cultivated adult human retinal pigment epithelial cells were encapsulated with different concentrations of fibrin glue, namely FG1 (42 mg/dl), FG2 (84 mg/dl), FG3 (124 mg/dl), FG4 (210 mg/dl), followed by the evaluation of genetic and cytomorphological changes and protein expression. Cultured adult human retinal pigment epithelial cells showed dendritiform morphology during the early days of encapsulation with fibrin glue. Moreover, an increasing inhibitory effect on cell growth was observed with increasing concentrations of fibrin glue. At the transcriptional level, the expression of MMP2, PAX6, and ITGB1 in FG1-encapsulated cells was significantly higher than that in other treated groups; however, the expression of ACTA2 was lower in all fibrin glue-encapsulated groups compared to that in the controls. Immunocytochemistry showed that FG2-encapsulated cells expressed cytokeratin 8/18, RPE65, and ZO-1 proteins, but not PAX6. In conclusion, fibrin glue at a concentration of 84 mg/dl allows proper encapsulation of adult human retinal pigment epithelial cells, while preserving the morphometric, genotypic, and phenotypic features of the cells. This three-dimensional biopolymer can be considered a reliable vehicle for retinal pigment epithelium cell transplantation in cell-based therapies.

ALLOGENEIC PLATELET-RICH PLASMA FOR ROTATOR CUFF REPAIR

OBJECTIVE

To investigate the safety and efficacy of allogeneic platelet-rich plasma (PRP) in rotator cuff repair .

METHODS

Seventeen patients with a full-thickness rotator cuff tear were included. Ten patients underwent arthroscopic rotator cuff repair with allogeneic, and seven patients with autologous PRP. Three PRP gels in a volume 3 ml each were applied between the torn end and the greater tuberosity. Clinical outcomes were assessed preoperatively and at a minimum of 2 years after surgery. Structural outcomes were evaluated with the presence of retear and the change of the cross-sectional area (ACT) of the supraspinatus .

RESULTS

Allogeneic PRP did not cause any adverse events during the follow-up period. There was no significant difference in the clinical outcome measures between the two groups (all p > 0.05). The retear rate was 33.3% and 25.0% in the allogeneic group and autologous group, respectively (p = 0.764). The change between the one-year postoperative and immediately postoperative ACT was not also significantly different between the two groups (p = 0.373) .

CONCLUSION

Allogeneic PRP in arthroscopic rotator cuff did not cause any local or general complications and that has the efficacy comparable to autologous PRP with respect to the clinical and structural outcomes. Level of Evidence III, Retrospective Comparative Study.

Platelet gel: a new therapeutic tool with great potential

Chronic wounds, such as diabetic foot ulcers, represent a serious clinical problem for patients and clinicians. Management of these wounds has a strong economic impact worldwide. Complications resulting from injuries are a frequent cause of morbidity and mortality. Chronic wounds lead to infections, painful dressings and prolonged hospitalisation. This results in poor patient Quality of Life and in high healthcare costs. Platelet concentrates (PC) are defined as autologous or allogeneic platelet derivatives with a platelet concentration higher than baseline. PC are widely used in different areas of Regenerative Medicine in order to enhance wound healing processes; they include platelet-rich plasma (PRP), platelet gel (PG), platelet-rich fibrin (PRF), serum eye drops (E-S), and PRP eye drops (E-PRP). This review highlights the use of platelet-rich plasma (PRP) and platelet gel (PG) preparation for clinical use.

Healing of a soft tissue wound of the neck and jaw osteoradionecrosis using platelet gel

AIM

Bone osteoradionecrosis is a serious complication of radiation treatment. Current treatment approaches are not curative and treatment response is often poor leading to high social and healthcare costs.

CASE REPORT

We report on the first case of osteoradionecrosis with successful restitutio ab integro by repeated administration of platelet gel (PLT-gel) and surgery in a critically ill patient. The administration of PLT-gel during a severe septic episode helped regeneration of bone and soft tissues, shortening the hospital stay of the patient. It was also noted that following applications of PLT-gel, both the use of morphine and the numbers of infective episodes were reduced.

CONCLUSION

Additional studies are needed to confirm the promising effect of PLT-gel for the treatment of osteoradionecrosis.

Autologous platelet-rich plasma for treating chronic wounds

BACKGROUND

Autologous platelet-rich plasma (PRP) is a treatment that contains fibrin and high concentrations of growth factors with the potential to improve the healing of chronic wounds. This is the first update of a review first published in 2012.

OBJECTIVES

To determine whether autologous PRP promotes the healing of chronic wounds.

SEARCH METHODS

In June 2015, for this first update, we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library): Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE; and EBSCO CINAHL. We also searched for ongoing and unpublished clinical trials in the WHO International Clinical Trials Registry Platform (ICTRP) (searched January 2015). We did not impose any restrictions with respect to language, date of publication, or study setting.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared autologous PRP with placebo or alternative treatments for any type of chronic wound in adults. We did not apply any date or language restrictions.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology, including two reviewers independently selecting studies for inclusion, extracting data, and assessing risk of bias.

MAIN RESULTS

The search identified one new RCT, making a total of 10 included RCTs (442 participants, 42% women). The median number of participants per RCT was 29 (range 10 to 117). Four RCTs recruited people with a range of chronic wounds; three RCTs recruited people with venous leg ulcers, and three RCTs considered foot ulcers in people with diabetes. The median length of treatment was 12 weeks (range 8 to 40 weeks).It is unclear whether autologous PRP improves the healing of chronic wounds generally compared with standard treatment (with or without placebo) (risk ratio (RR) 1.19, 95% confidence interval (CI) 0.95 to 1.50; I(2) = 27%, low quality evidence, 8 RCTs, 391 participants). Autologous PRP may increase the healing of foot ulcers in people with diabetes compared with standard care (with or without placebo) (RR 1.22, 95% CI 1.01 to 1.49; I(2) = 0%, low quality evidence, 2 RCTs, 189 participants). It is unclear if autologous PRP affects the healing of venous leg ulcers (RR 1.02, 95% CI 0.81 to 1.27; I(2) = 0% ). It is unclear if there is a difference in the risk of adverse events in people treated with PRP or standard care (RR 1.05, 95% CI 0.29 to 3.88; I(2) = 0%, low quality evidence from 3 trials, 102 participants).

AUTHORS' CONCLUSIONS

PRP may improve the healing of foot ulcers associated with diabetes, but this conclusion is based on low quality evidence from two small RCTs. It is unclear whether PRP influences the healing of other chronic wounds. The overall quality of evidence of autologous PRP for treating chronic wounds is low. There are very few RCTs evaluating PRP, they are underpowered to detect treatment effects, if they exist, and are generally at high or unclear risk of bias. Well designed and adequately powered clinical trials are needed.

Multicentre standardisation of a clinical grade procedure for the preparation of allogeneic platelet concentrates from umbilical cord blood

BACKGROUND

In addition to a largely prevalent use for bleeding prophylaxis, platelet concentrates from adult blood have also been used for many years to prepare platelet gels for the repair of topical skin ulcers. Platelet gel can be obtained by activation of fresh, cryopreserved, autologous or allogeneic platelet concentrates with calcium gluconate, thrombin and/or batroxobin. The high content of tissue regenerative factors in cord blood platelets and the widespread availability of allogeneic cord blood units generously donated for haematopoietic transplant but unsuitable for this use solely because of low haematopoietic stem cell content prompted us to develop a national programme to standardise the production of allogeneic cryopreserved cord blood platelet concentrates (CBPC) suitable for later preparation of clinical-grade cord blood platelet gel.

MATERIALS AND METHODS

Cord blood units collected at public banks with total nucleated cell counts <1.5×10(9), platelet count >150×10(9)/L and volume >50 mL, underwent soft centrifugation within 48 hours of collection. Platelet-rich plasma was centrifuged at high speed to obtain a CBPC with target platelet concentration of 800-1,200×10(9)/L, which was cryopreserved, without cryoprotectant, below -40 °C.

RESULTS

During 14 months, 13 banks produced 1,080 CBPC with mean (± standard deviation) volume of 11.4±4.4 mL and platelet concentration of 1,003±229×10(9)/L. Total platelet count per CBPC was 11.3±4.9×10(9). Platelet recovery from cord blood was 47.7±17.8%. About one-third of cord blood units donated for haematopoietic transplant could meet the requirements for preparation of CBPC. The cost of preparation was € 160.92/CBPC. About 2 hours were needed for one technician to prepare four CBPC.

DISCUSSION

This study yielded valuable scientific and operational information regarding the development of clinical trials using allogeneic CBPC.

Use of allogeneic platelet gel in the management of chemotherapy extravasation injuries: a case report

The allogeneic platelet (PLT) gel offers to be a valid supportive measure in the management of chemotherapy extravasation injuries. We report a case of a 58-year-old patient with multiple myeloma enrolled for high-dose chemotherapy and autologous stem cell transplantation. As pretransplant therapy, the patient received induction therapy with bortezomib, adriblastina, and desametazone. A port was inserted in the vein on the back of the hand. After three cycles, the patient reported rapid development of redness, pain, and necrotic tissue in the left hand, and a diagnosis of extravasation was addressed. The patient presented a raw area on the back of the hand caused by cytotoxic/chemotherapeutic drug leakage because of the malposition of venous access devices. Skin ulcer was debrided, and the wound was reconstructed with a combination of local random rotational flap and abdomen skin graft. Two weeks later, a 20% skin flap necrosis was observed. In the context of wound healing, topical plasma-rich PLT gel is able to accelerate the regeneration and repair of tissue, so it was set out to assess PLT gel efficacy in this case. The PLT gel was applied topically once every 5 days, for a duration of 60 days on average. There were no adverse reactions observed during the topical therapy. Complete wound healing was observed after 12 PLT-rich plasma applications. No ulcer recurrence was noted in the patient during the follow-up period of 2–19 months.

Cord blood platelet gel treatment of dystrophic recessive epidermolysis bullosa

Epidermolysis bullosa (EB) is comprised of a group of hereditary mechanobullous disorders that are characterised by extremely fragile skin and mucous membranes. This results in blister formation and non-healing wounds. This case report describes the results of an innovative treatment of two large skin lesions in a newborn with dystrophic recessive EB (DEB) who experienced bacterial superinfections and progressive anaemisation. The lesions were treated with platelet gels derived from allogeneic cord blood (cord blood platelet gel, CBPGs). The skin lesions were clinically evaluated and treated with CBPG weekly until they completely healed. The first and second lesion required CBPG applications for 2 and 4 weeks, respectively. Both lesions were monitored weekly for 6 weeks after the last CBPG application, and no significant relapses were observed during the follow-up period. This case indicates that CBPG is an effective and safe therapeutic option for managing newborns with DEB, particularly as treatment and prevention of fluid loss and superinfection.

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.

Umbilical cord blood banking: from personal donation to international public registries to global bioeconomy

The procedures for collecting voluntarily and freely donated umbilical cord blood (UCB) units and processing them for use in transplants are extremely costly, and the capital flows thus generated form part of an increasingly pervasive global bioeconomy. To place the issue in perspective, this article first examines the different types of UCB biobank, the organization of international registries of public UCB biobanks, the optimal size of national inventories, and the possibility of obtaining commercial products from donated units. The fees generally applied for the acquisition of UCB units for transplantation are then discussed, and some considerations are proposed regarding the social and ethical implications raised by the international network for the importation and exportation of UCB, with a particular emphasis on the globalized bioeconomy of UCB and its commerciality or lack thereof.

Treatment of life-threatening wounds with a combination of allogenic platelet-rich plasma, fibrin glue and collagen matrix, and a literature review

Currently there is no ideal procedure for the treatment of recalcitrant ulcers that are unresponsive to the majority of common treatments. However, several novel approaches have been proposed, including bone marrow stem cells, platelets, fibrin glue and collagen matrix. For the first approach treatment of a chronic wound, a non-invasive method is highly desirable. The present study was undertaken with the aim of evaluating the effect of a combination of platelets, fibrin glue and collagen matrix (PFC) in one treatment. A total of ten patients with aggressive, refractory, life-threatening wounds were recruited for the study and their treatment effects were evaluated. Initially, the ulcers were extensively debrided, measured and photographed at weekly intervals. The PFC combination was applied topically to the wound every two days. Following treatment, the wound was completely closed in nine patients and was markedly reduced in the other patient. The mean 100% healing time for the nine patients was 11.3±5.22 weeks. There was no evidence of local or systemic complications or any abnormal tissue formation, keloid or hypertrophic scarring. Therefore, the results of the present study indicate that in the first approach, the combination of PFC components may be used safely in order to synergize the effect of chronic wound healing.

Autologous Platelet Gel

Leg ulcers represent a particularly disabling complication in patients with sickle cell disease (SCD). Platelet gel (PG) is a novel therapeutic strategy used for accelerating wound healing of a wide range of tissues through the continuous release of platelet growth factors. Here, we describe the use of PG preparation according to Anitua’s PRGF (preparations rich in growth factors) protocol for treating chronic nonhealing ulcers in patients with SCD. A positive response occurred in 3 patients with an area reduction of 85.7% to 100%, which occurred within 7 to 10 weeks, and a 35.2% and 20.5% of area reduction in 2 other patients, who however, had large ulcers. After calcium chloride addition, the platelet-rich plasmas demonstrated enhanced platelet-derived growth factors–BB ( P < .001), transforming growth factor-β1 ( P = .015), vascular endothelial growth factors ( P = .03), and hepatocyte growth factors (nonsignificant) secretion. Furthermore, calcium chloride addition induced a significant decrease in platelet number ( P = .0134) and there was no leukocyte detection in the PG product. These results demonstrate that PG treatment might impact the healing of leg ulcers in sickle cell disease, especially in patients with small ulcers.

Pleural tissue repair with cord blood platelet gel

BACKGROUND

Prolonged air leak is the major cause of morbidity after pulmonary resection. In this study we used in vitro and in vivo experiments to investigate an innovative approach based on the use of human umbilical cord blood platelet gel.

MATERIALS AND METHODS

In vitro, a scratch assay was performed to test the tissue repair capability mediated by cord blood platelet gel compared to the standard culture conditions using human primary mesothelial cells. In vivo, an iatrogenic injury was made to the left lung of 54 Wistar rats. Cord blood platelet gel was placed on the injured area only in treated animals and at different times histological changes and the presence of pleural adhesions were evaluated. In addition, changes in the pattern of soluble inflammatory factors were investigated using a multiplex proteome array.

RESULTS

In vitro, mesothelial cell damage was repaired in a shorter time by cord blood platelet gel than in the control condition (24 versus 35 hours, respectively). In vivo, formation of new mesothelial tissue and complete tissue recovery were observed at 45±1 and 75±1 hours in treated animals and at 130±2.5 and 160±6 hours in controls, respectively. Pleural adhesions were evident in 43% of treated animals compared to 17% of controls. No complications were observed. Interestingly, some crucial soluble factors involved in inflammation were significantly reduced in treated animals.

DISCUSSION

Cord blood platelet gel accelerates the repair of pleural damage and stimulates the development of pleural adhesions. Both properties could be particularly useful in the management of prolonged air leak, and to reduce inflammation.

Ultrastructural characteristics of fibrin clots from canine and feline platelet concentrates activated with calcium gluconate or calcium gluconate plus batroxobin

Background

The aim of this study was to use transmission electron microscopy to describe the ultrastructural characteristics of clots obtained from canine and feline platelet concentrates (PC) that had been activated with calcium gluconate (CG) or CG plus batroxobin (CGB). Platelets from fibrin clots were classified according their morphological changes. The area of the intercellular space (μm²), the area of the fibrin fibers (μm²), and the width of the fibrin fibers (μm) were determined for the dog clots. The platelet area (μm²), the area of fibrin fibers (μm²), the ratio of the minor and major axes of platelets, the ratio of the major and minor axes of platelets, and the number of α-granules found within platelets were measured for the cat clots.

Results

Cat platelets displayed full activation. Dog platelets displayed lysis with loss of normal architecture. In both species, a statistically significant difference was found (P < 0.01) between the fibrin fiber measurements in the PC clots activated with CG and CGB.

Conclusions

The findings suggest that activation with CG caused platelet alpha granules to release their contents. In cats, fibrin production was greater when the PC was activated with CG. In dogs, activation with CG produced thick fibrin fibers.

Treatment of nonhealing diabetic lower extremity ulcers with skin graft and autologous platelet gel: a case series

Lower extremity ulcers in diabetic patients are difficult to treat. Recently, the use of human blood platelet-derived components in this indication has been raising interest. In this study, we have evaluated the safety and efficacy of the combination of autologous platelet gel (PG) and skin graft for treating large size recalcitrant ulcers. Eight consecutive diabetic patients aged 25 to 82 with nine nonhealing lower extremity ulcers (median size of 50 cm²; range 15–150 cm²) were treated. Skin ulcer was debrided, and the wound was sprayed after 7 to 10 days with autologous platelet-rich plasma and thrombin. Thin split-thickness skin graft with multiple slits was then applied on the wound bed and fixed with staples or cat-gut sutures. There were no adverse reactions observed during the study. Eight out of 9 skin grafts took well. The interval between skin graft and complete wound healing ranged from 2 to 3 weeks in the 8 successful cases. No ulcer recurrence was noted in those patients during the follow-up period of 2 to 19 months. In this study, the combination of autologous platelet gel and skin grafting has proven beneficial to heal large-size recalcitrant ulcers.

Characteristics of an autologous leukocyte and platelet-rich fibrin patch intended for the treatment of recalcitrant wounds

We have investigated the physical, biochemical, and cellular properties of an autologous leukocyte and platelet-rich fibrin patch. This was generated in an automated device from a sample of a patient's blood at the point of care. Using microscopy, cell counting, enzyme-linked immunosorbent assay, antibody arrays, and cell culture assays, we show that the patch is a three-layered membrane comprising a fibrin sheet, a layer of platelets, and a layer of leukocytes. Mean recovery of platelets from the donated blood was 98% (±95%CI 0.8%). Mean levels of platelet-derived growth factor AB, human transforming growth factor beta 1, and vascular endothelial growth factor extracted from the patch were determined as 127 ng (±95% CI 20), 92 ng (±95%CI 17), and 1.35 ng (±95%CI 0.37), respectively. We showed a continued release of PDGF-AB over several days, the rate of which was increased by the addition of chronic wound fluid. By comparison with traditional platelet-rich plasma, differences in immune components were found. The relevance of these findings was assessed by showing a mitogenic and migratory effect on cultured human dermal fibroblasts. Further, we showed that fibrocytes, a cell type important for acute wound healing, could be grown from the patch. The relevance of these findings in relation to the use of the patch for treating recalcitrant wounds is discussed.

Recalcitrant cutaneous ulcer of comorbid patient treated with platelet rich plasma: a case report

The platelet-rich plasma (PRP) has been advocated as a way to introduce increased concentrations of growth factors and other bioactive molecules to injured tissues in an attempt to optimize the local healing environment. A 94-yr-old woman with various comorbidities presented with a two-week history of severe cutaneous ulcer on the left dorsum of foot. It was caused by recurrent mechanical trauma and did not respond to several wound debridement and simple dressings. However, after she was completed on seven times of autologous PRP treatments, we observed complete healing of the skin lesion within 3 months. Herein, we report a case of recalcitrant cutaneous ulcer with various comorbidities and discuss about the promising possibility of autologous PRP as an effective alternative therapeutic modality.

Evaluation of the effect of calcium gluconate and bovine thrombin on the temporal release of transforming growth factor beta 1 and platelet-derived growth factor isoform BB from feline platelet concentrates

BACKGROUND

There are not reported regarding the protocols for obtaining platelet concentrates (PC) in cats for medical purposes. The objectives of this study were: 1) to describe a manual method for producing two kinds of PC in cats (PC-A and PC-B), 2) to describe the cellular population of the PC, 3) to measure and compare the effect of calcium gluconate (CG) and bovine thrombin (BT) on the temporal release of transforming growth factor beta 1 (TGF-β1) and platelet-derived growth factor type BB (PDGF-BB) at 3 and 12 hours post-activation and 4) to establish correlations between the cellular population of both PCs and the concentration of growth factors (GF). Blood samples were taken from 16 cats for complete blood count, plasma collection and PC preparation. The PC were arbitrarily divided into two fractions, specifically, PC-A (lower fraction) and PC-B (upper fraction).

RESULTS

The platelet counts were significantly different (P<0.05) between the PC and whole blood but not between the PC fractions. The TGF-β1 concentration efficiencies for PC-A and PC-B activated with CG were 42.86% and 46.54%, and activated with BT were 42.88% and 54.64%, respectively. The PDGF-BB concentration efficiencies for PC-A and PC-B activated with CG were 61.36% and 60.61%, and activated with BT were 65.64% and 72.12%, respectively. The temporal release of GFs showed no statistically significant difference (P>0.05) between the activating substances at the time or for any PC fraction.

CONCLUSIONS

Whatever the activation means, these preparations of cat PC provide significant concentrations of platelets and GFs for possible clinical or experimental use.

Ethical and legal considerations regarding the ownership and commercial use of human biological materials and their derivatives

This article considers some of the ethical and legal issues relating to the ownership and use - including for commercial purposes - of biological material and products derived from humans. The discussion is divided into three parts: after first examining the general notion of ownership, it moves to the particular case of possible commercial use, and finally reflects on the case in point in the light of the preceding considerations. Units of cord blood donated altruistically for transplantation and which are found unsuitable for storage and transplantation, or which become unsuitable while stored in biobanks, are taken as an example. These cord-blood units can be discarded together with other biological waste, or they can be used for research or the development of blood-derived products such as platelet gel. Several ethical questions (eg, informed consent, property, distribution of profits, and others) arise from these circumstances. In this regard, some criteria and limits to use are proposed.

Comparison of the effect of calcium gluconate and batroxobin on the release of transforming growth factor beta 1 in canine platelet concentrates

Background

The clinical use of autologous platelet concentrates (also known as platelet-rich plasma) on the field of regenerative therapy, in the last decade has been the subject of several studies especially in equine medicine and surgery. The objectives of this study was: 1) to describe and compare the cellular population in whole blood, lower fraction (A) and upper fraction (B) of platelet concentrates, 2) to measure and compare the transforming growth factor beta 1 (TGF-β₁) concentration in plasma and both platelet concentrates after be activated with calcium gluconate or batroxobin plus calcium gluconate and, 3) to determine correlations between cell counts in platelet concentrates and concentrations of TGF-β₁. Blood samples were taken from 16 dogs for complete blood count, plasma collection and platelet concentrates preparation. The platelet concentrates (PC) were arbitrarily divided into two fractions, specifically, PC-A (lower fraction) and PC-B (upper fraction). The Platelet concentrates were analyzed by hemogram. After activated with calcium gluconate or batroxobin plus calcium gluconate, TGF-β₁ concentration was determined in supernatants of platelet concentrates and plasma.

Results

There were differences statistically significant (P < 0.05) for the platelet count and leukocyte count and TGF-β₁ concentration between whole blood, plasma and both platelet concentrates. A significant correlation was found between the number of platelets in both platelet concentrates and TGF-β₁ concentration. Platelet collection efficiency was 46.34% and 28.16% for PC-A and PC-B, respectively. TGF-β₁ concentration efficiency for PC activated with calcium gluconate was 47.75% and 31.77%, for PC-A and PC-B, respectively. PC activated with batroxobin plus CG showed 46.87% and 32.24% for PC-A and PC-B, respectively.

Conclusions

The methodology used in this study allows the concentration of a number of platelets and TGF-β₁ that might be acceptable for a biological effect for clinical or experimental use as a regenerative therapy in dogs.

"Reasonable compromise" to define the quality standards of platelet concentrate for non-transfusion use (CPunT)

Platelets concentrate for non-transfusion use (CPunT) is a blood component specific for regenerative medicine. This blood component has found regenerative applications in many clinical fields (orthopedic, plastic surgery, maxillofacial surgery) since platelets contain growth factors, cytokines and bioactive molecules. Plasticity and ease of preparation of this blood component has often led the user to prepare it without using standardized procedures and references to quality product standards, but to evaluate the effectiveness of treatments and to standardize clinical protocols, is essential. The complexity of establish functional and non-functional parameters to define CPunT properties is linked to three fundamental steps: variability and bioavailability of biomolecules content in platelets, variability in product preparation. Then it is very difficult to understand which are the real parameters to evaluate, but it seems a "reasonable compromise" to establish content of platelets×ml (1×10(9)ml) as reference realistic parameter for CPunT qualification.

Antimicrobial activity of platelet (PLT)-poor plasma, PLT-rich plasma, PLT gel, and solvent/detergent-treated PLT lysate biomaterials against wound bacteria

BACKGROUND

Platelet (PLT) gels exhibit antimicrobial activity useful for wound healing. The nature of the antibacterial component(s) is unknown.

STUDY DESIGN AND METHODS

PLT-poor plasma (PPP), PLT-rich plasma (PRP), PLT gel (PG), and solvent/detergent-treated PLT lysate (S/D-PL) from two donors were evaluated either native or after complement heat inactivation. Materials were spiked at a 10% ratio (vol/vol) with approximately 10(7-8) colony-forming units/mL with four Gram-positive and four Gram-negative bacteria of the wound flora. Bacterial count was determined by plate assays at time of spiking and after 3 and 48 hours at 31°C. Bacteria growth inhibition tests were also performed.

RESULTS

There was no viable Escherichia coli colony for 48 hours after spiking to the plasma and PLT materials from both donors, corresponding to greater than 7.51 to greater than 9.05 log inactivation. Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus were inactivated (approx. 4.7, 7, and 2 log, respectively) 3 hours after spiking to PRP, PPP, or S/D-PL from the first donor but less (1.1, 4.6, and 0.2 log, respectively) in PG, before a regrowth at 48 hours in all materials. Similar data were obtained with the second donor. No plasma and PLT material had antimicrobial activity against Enterobacter cloacae, Bacillus cereus, Bacillus subtilis, and Staphylococcus epidermidis. Complement-inactivated samples had no antimicrobial activity.

CONCLUSION

Plasma complement is mostly responsible for the activity of plasma and PLT biomaterials against E. coli, P. aeruginosa, K. pneumoniae, and S. aureus. Activation of the coagulation to prepare PG may reduce antimicrobial activity. These findings may help optimize the control of wound infections by blood biomaterials.