Regenerative effect of expired platelet concentrates in human therapy: An update.

There is concrete evidence that outdated allogeneic platelet concentrates not used for transfusion are valuable sources of functional trophic factors, including growth factors, cytokines, chemokines, anti-inflammatory and antioxidant molecules. Such outdated platelet concentrates can be used to produce human platelet lysates (HPL), a proven potent growth supplement for the propagation of therapeutic human cells, including mesenchymal stromal cells. On-going preclinical studies demonstrate the interest in such "outdated" allogeneic platelet lysates for treating corneal diseases and neurological disorders of the central nervous system, potentially opening vital therapeutic perspectives.

Platelet microparticle: a sensitive physiological "fine tuning" balancing factor in health and disease.

Platelet microparticles (PMPs) have long been regarded as inert "platelet dusts". They have now taken a center stage on the clinical research scene of transfusion medicine, being actually seen as long-stretch hands of platelets that exert a physiological role beyond the initial site of activation. These 0.05 µm to 0.8 µm microvesicles, delimited by a phospholipidic bilayer, are released by platelet membranes following activation by agonists, complement activation, or high shear forces. They can also be generated as a result of platelets and megakaryocyte senescence or cytoskeletal abnormalities. PMPs may orchestrate a delicate hemostatic balance in health, and act as procoagulant vectors in diseases triggering thrombosis. Furthermore, through their potential cargo of growth factors, microRNA and various bioactive molecules, they may promote healing in health, but, on the other side of the coin, can act as pro-inflammatory carriers and may contribute to cancer growth as an actor of the platelet-cancer loop. Through their cellular interactions they also interplay with the immune system. Their capacity to be generated by shear forces and contact with surfaces during the processing of blood and blood components, which may trigger transfusion reactions, make them also an integral part of transfusion medicine. Given their documented association with pathological conditions, PMP may serve as biomarkers for disease status or as a possible new target for anti-platelet drugs to treat cancer or inflammation.

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.

Platelet microparticles: detection and assessment of their paradoxical functional roles in disease and regenerative medicine.

There is increasing research on and clinical interest in the physiological role played by platelet microparticles (PMPs). PMPs are 0.1-1-µm fragments shed from plasma membranes of platelets that are undergoing activation, stress, or apoptosis. They have a phospholipid-based structure and express functional receptors from platelet membranes. As they are the most abundant microparticles in the blood and they express the procoagulant phosphatidylserine, PMPs likely complement, if not amplify, the functions of platelets in hemostasis, thrombosis, cancer, and inflammation, but also act as promoters of tissue regeneration. Their size and structure make them instrumental in platelet-cell communications as a delivery tool of platelet-borne bioactive molecules including growth factors, other signaling molecules and micro (mi)RNA. PMPs can therefore be a pathophysiological threat or benefit to the cellular environment when interacting with the blood vasculature. There is also increasing evidence that PMP generation is triggered during blood collection, separation into components, and storage, a phenomenon potentially leading to thrombotic and inflammatory side effects in transfused patients. Evaluating PMPs requires strict pre-analytical and analytical procedures to avoid artifactual generation and ensure accurate assessment of the number, size repartitioning, and functional properties. This review describes the physical and functional methods developed for analyzing and quantifying PMPs. It then presents the functional roles of PMPs as markers or triggers of diseases like thrombosis, atherosclerosis, and cancer, and discusses the possible detrimental immunological impact of their generation in blood components. Finally we review the potential function of PMPs in tissue regeneration and the prospects for their use in therapeutic strategies for human health.

Blood-derived biomaterials and platelet growth factors in regenerative medicine.

Several biomaterials can be obtained from human blood. Some are used for clinical indications requiring a high content in fibrinogen, while others are used because they contain multiple platelet growth factors. Mimicking thrombin-induced physiological events of coagulation leading to fibrino-formation and platelet activation, blood biomaterials have critical advantages of being devoid of tissue necrotic effects and of being biodegradable by body enzymes. Fibrin-based biomaterials, known as fibrin glues or fibrin sealants, have been used for more than 30 years as surgical hemostatic and sealing agents, demonstrating benefits in essentially all surgical fields, including reconstructive plastic surgery and wound treatment. Clinical interest in platelet growth factor-rich biomaterials (often known as platelet gels or platelet-rich-plasma) has emerged more recently. Platelet gels are used in clinical situations to achieve wound healing and repair soft and hard tissues. Applications include the healing of recalcitrant ulcers and burns, and stimulation of osseous tissue regeneration in dentistry, implantology, and maxillofacial and plastic surgery. They were evaluated recently in knee osteoarthritis and for the repair of musculoskeletal tissue lesions in sports medicine. Platelet lysates are now used as a substitute for fetal bovine serum and for ex vivo clinical-scale expansion of stem cells, opening new perspectives in regenerative medicine. We present the scientific rationale that prevailed in the development of blood biomaterials, describe their modes of production and biochemical and functional characteristics, and present clinical applications in regenerative medicine.

Failure of a non-authorized copy product to maintain response achieved with imatinib in a patient with chronic phase chronic myeloid leukemia: a case report.

INTRODUCTION: Due to high rates of response and durable remissions, imatinib (Glivec((R)), or Gleevec((R)) in the USA; Novartis Pharma AG) is the standard of care in patients with chronic myeloid leukemia. Recently, a non-authorized product which claims comparability to imatinib has become available. CASE PRESENTATION: This report describes the loss of response in a 36-year-old male patient with chronic-phase chronic myeloid leukemia who had previously been in full hematologic and cytogenetic remission and partial molecular remission for three years, under treatment with brand-name imatinib of 400 mg per day. Before the initiation of treatment with a copy product, imatib (CIPLA-India), the patient had negative BCR-ABL status. Within three months of initiation of treatment with the copy product, the patient's BCR-ABL status became positive, with substantial decreases noted in white blood cell counts, red blood cell counts and platelet counts. Conversion of the BCR-ABL status to negative and improvements in hematologic parameters were achieved when the brand medication, imatinib, was resumed at a dose of 600 mg per day. CONCLUSION: In our patient, the substitution of a copy product for imatinib resulted in the rapid loss of a previously stable response, with the risk of progression to life-threatening accelerated phase or blast crisis phase of the disease. Without supportive clinical evidence of efficacy and safety of imatib (or any other copy product) caution should be used when substituting imatinib in the treatment of any patient with chronic myeloid leukemia.

Impact of Triton X-100 on alpha 2-antiplasmin (SERPINF2) activity in solvent/detergent-treated plasma.

Large-pool solvent/detergent (SD) plasma for transfusion exhibits reduced alpha 2-antiplasmin (alpha2-AP; SERPINF2) functional activity. The reason for the loss of alpha2-AP has not been described and could be due to the SD incubation itself and/or to the processing steps implemented to remove the solvent and the detergent. We have studied alpha2-AP activity during six down-scale preparations of plasma virally-inactivated by 1% (v/v) TnBP combined with two different non-ionic detergents, either 1% Triton X-100 or 1% Triton X-45, at 31 degrees C for 4h. The SD-treated plasmas were then extracted with 7.5% (v/v) soybean oil, centrifuged at 3800 x g for 30 min, and subjected to hydrophobic interaction chromatography (HIC) to remove the SD agents. Control runs without TnBP and Triton were performed to evidence possible impacts of each process step on alpha2-AP activity. TnBP, Triton X-100, and Triton X-45 were measured at all stages of the processes to evaluate potential interferences with the alpha2-AP assay. Alpha 2-AP activity was about 10% that of starting plasma after 1% TnBP-1% Triton X-100 incubation and about 50% after oil extractions, centrifugation, and HIC. By contrast about 73% of the antiplasmin activity was found after the incubation with 1% TnBP and 1% Triton X-45, 88% after removal of the SD agents by oil extractions, 90% after centrifugation and 92% after HIC. The control runs performed without SD agents showed that the process steps did not affect the alpha2-AP activity. In conclusion, the agent altering alpha2-AP activity in SD-plasma is Triton X-100. The choice of detergents for the SD viral inactivation of therapeutic plasma fractions used in patients at risk of fibrinolysis should consider the impact on alpha2-AP activity.

A process for solvent/detergent treatment of plasma for transfusion at blood centers that use a disposable-bag system.

BACKGROUND: Solvent/detergent (S/D) inactivates enveloped viruses in plasma. The current technology requires a plasma fractionation facility and is applied to large plasma pools, which increases the cost and risks of exposure to S/D-resistant pathogens and lowers the content of protein S and alpha2-antiplasmin. Two S/D treatment procedures for single donations or minipools of plasma have been developed with a single-use bag system. STUDY DESIGN AND METHODS: Frozen plasma samples were thawed and treated in disposable bags with either 2 percent tri(n-butyl)phosphate (TnBP) at 37 degrees C or 1 percent TnBP and 1 percent Triton X-45 at 31 degrees C for 4 hours. Plasma samples were extracted three times with 7.5 percent sterile castor oil to remove TnBP and Triton X-45. The TnBP-treated plasma samples were further subjected to a clarifying centrifugation (3800 x g, 30 min). Final plasma samples were dispensed into individual bags and frozen at -30 degrees C. Plasma quality was assessed at each step of the procedures. RESULTS: Both processes yielded greater than 90 percent mean recovery of coagulation factors (clottable fibrinogen, von Willebrand factor, and factors VIII, V, VII, IX, X, and XI), anticoagulants (protein C, protein S), protease inhibitors (antithrombin, alpha2-antiplasmin), total protein, albumin, and immunoglobulins. Global coagulation tests of the treated plasma samples were normal. Final TnBP and Triton X-45 content was less than 10 and 50 ppm, respectively. CONCLUSION: S/D treatment of plasma can be performed in a closed-bag system under conditions that maintain plasma protein quality. The technology is simple, presents advantages over the industrial large-scale S/D plasma process, and could be performed in blood centers.