Tailor-made purified human platelet lysate concentrated in neurotrophins for treatment of Parkinson's disease

Neuroprotective effects of intranasal extracellular vesicles from human platelet concentrates supernatants in traumatic brain injury and Parkinson's disease models

BACKGROUND

The burgeoning field of regenerative medicine has significantly advanced with recent findings on biotherapies using human platelet lysates (HPLs), derived from clinical-grade platelet concentrates (PCs), for treating brain disorders. These developments have opened new translational research avenues to explore the neuroprotective effects of platelet-extracellular vesicles (PEVs). Their potential in managing neurodegenerative conditions like traumatic brain injury (TBI) and Parkinson's disease (PD) warrants further exploration. We aimed here to characterize the composition of a PEV preparation isolated from platelet concentrate (PC) supernatant, and determine its neuroprotective potential and neurorestorative effects in cellular and animal models of TBI and PD.

METHODS

We isolated PEVs from the supernatant of clinical-grade PC collected from healthy blood donors utilizing high-speed centrifugation. PEVs were characterized by biophysical, biochemical, microscopic, and LC-MS/MS proteomics methods to unveil biological functions. Their functionality was assessed in vitro using SH-SY5Y neuronal cells, LUHMES dopaminergic neurons, and BV-2 microglial cells, and in vivo by intranasal administration in a controlled cortical impact (CCI)-TBI model using 8-weeks-old male C57/BL6 mice, and in a PD model induced by MPTP in 5-month-old male C57/BL6 mice.

RESULTS

PEVs varied in size from 50 to 350 nm, predominantly around 200 nm, with concentrations ranging between 1010 and 1011/mL. They expressed specific platelet membrane markers, exhibited a lipid bilayer by cryo-electron microscopy and, importantly, showed low expression of pro-coagulant phosphatidylserine. LC-MS/MS indicated a rich composition of trophic factors, including neurotrophins, anti-inflammatory agents, neurotransmitters, and antioxidants, unveiling their multifaceted biological functions. PEVs aided in the restoration of neuronal functions in SH-SY5Y cells and demonstrated remarkable neuroprotective capabilities against erastin-induced ferroptosis in dopaminergic neurons. In microglial cells, they promoted anti-inflammatory responses, particularly under inflammatory conditions. In vivo, intranasally delivered PEVs showed strong anti-inflammatory effects in a TBI mouse model and conserved tyrosine hydroxylase expression of dopaminergic neurons of the substantia nigra in a PD model, leading to improved motor function.

CONCLUSIONS

The potential of PEV-based therapies in neuroprotection opens new therapeutic avenues for neurodegenerative disorders. The study advocates for clinical trials to establish the efficacy of PEV-based biotherapies in neuroregenerative medicine.

Growth factor and cytokine characterization of canine platelet lysate with variable leukocyte concentration, plasma content, and heat-sensitive proteins

Background

Platelet lysate is an acellular platelet product containing factors released from secretory granules, including cytokines and growth factors. This study aimed to evaluate different centrifugation methods used to prepare canine platelet lysate with variable content of leukocytes, plasma, and heat-sensitive proteins.

Methods

Whole blood was collected from six dogs and two double-spin preparation methods were used to generate the platelet-rich plasma with reduced (PRP) and high (L-PRP) concentration of leukocytes. A portion of both methods underwent plasma depletion via centrifugation and platelet lysate was generated via freeze-thaw cycles. A portion of the generated platelet lysate underwent complement inactivation via heat treatment. Growth factors (TGF-β1, VEGF, TNF-α, PDGF-BB, HGF) were quantified in all different platelet lysate preparations using ELISAs.

Results

Both platelet-rich plasma preparations had a 6.7-fold increase in platelet concentration. White blood cell (WBC) concentration compared to whole blood increased 1.2-fold times in PRP and 1.9-fold times in L-PRP. Negligible concentrations of platelets, WBC, and hematocrit were identified in all lysate groups. Statistically significant differences were identified for PDGF, VEGF, and TNF-α, and not for TGF-β or HGF. No growth factor differences were noted between centrifugation methods. PDGF was significantly higher in platelet lysate that was plasma depleted. VEGF was significantly higher in heat-treated lysate groups. TNF-α concentrations were overall very low, though were noted to significantly increase following plasma depletion.

Conclusion

These results support that growth factors and cytokine release can be affected by the platelet lysate preparation and processing.

Human platelet lysate supports SH-SY5Y neuroblastoma cell proliferation and differentiation into a dopaminergic-like neuronal phenotype under xenogeneic-free culture conditions

SH-SY5Y is a human neuroblastoma cell line that can be differentiated into several neuronal phenotypes, depending on culture conditions. For this reason, this cell line has been widely used as an in vitro model of neurodegenerative conditions, such as Parkinson's disease (PD). However, most studies published to date used fetal bovine serum (FBS) as culture medium supplement for SH-SY5Y cell differentiation. We report on the testing of human platelet lysate (hPL) as a culture medium supplement to support SH-SY5Y cell culture. Both standard hPL and a fibrinogen-depleted hPL (FD-hPL) formulation, which does not require the addition of anticoagulants to culture media, promoted an increase in SH-SY5Y cell proliferation in comparison to FBS, without compromising metabolic activity. SH-SY5Y cells cultured in hPL or FD-hPL also displayed a higher number of neurite extensions and stained positive for MAP2 and synaptophysin, in the absence of differentiation stimuli; reducing hPL or FD-hPL concentration to 1% v/v did not affect cell proliferation or metabolic activity. Furthermore, following treatment with retinoic acid (RA) and further stimulation with brain-derived neurotrophic factor (BDNF) and nerve growth factor beta (NGF-β), the percentage of SH-SY5Y cells stained positive for dopaminergic neuronal differentiation markers (tyrosine hydroxylase [TH] and Dopamine Transporter [DAT]) was higher in hPL or FD-hPL than in FBS, and gene expression of dopaminergic markers TH, DAT, and DR2 was also detected. Overall, the data herein presented supports the use of hPL to differentiate SH-SY5Y cells into a neuronal phenotype with dopaminergic features, and the adoption of FD-hPL as a fully xenogeneic free alternative to FBS to support the use of SH-SY5Y cells as a neurodegeneration model.

Proteomics of human platelet lysates and insight from animal studies on platelet protein diffusion to hippocampus upon intranasal administration

Human platelet lysates (HPLs) from allogeneic platelet concentrates (PCs) are biomaterials, which are rich in various trophic factors, increasingly used in regenerative medicine and biotherapy. Understanding how preparation methods influence the HPL protein profile, biological function, and clinical outcomes is crucial. Our study sheds light on the proteomes and functionality of different HPLs, with the aim of advancing their scientifically grounded clinical applications. To achieve this, PCs suspended in plasma underwent three distinct processing methods, resulting in seven HPL types. We used three characterization techniques: label-free proteomics and tandem mass tag (TMT)-based quantitative proteomics, both before and after the immunodepletion of abundant plasma proteins. Bioinformatic tools assessed the proteome, and western blotting validated our quantitative proteomics data. Subsequent pre-clinical studies with fluorescent labeling and label-free proteomics were used as a proof of concept for brain diffusion. Our findings revealed 1441 proteins detected using the label-free method, 952 proteins from the TMT experiment before and after depletion, and 1114 proteins from the subsequent TMT experiment on depleted HPLs. Most detected proteins were cytoplasmic, playing key roles in catalysis, hemostasis, and immune responses. Notably, the processing methodologies significantly influenced HPL compositions, their canonical pathways, and, consequently, their functionality. Each HPL exhibited specific abundant proteins, providing valuable insight for tailored clinical applications. Immunoblotting results for selected proteins corroborated our quantitative proteomics data. The diffusion and differential effects to the hippocampus of a neuroprotective HPL administered intranasally to mice were demonstrated. This proteomics study advances our understanding of HPLs, suggesting ways to standardize and customize their production for better clinical efficacy in regenerative medicine and biotherapy. Proteomic analyses also offered objective evidence that HPPL, upon intranasal delivery, not only effectively diffuses to the hippocampus but also alters protein expression in mice, bolstering its potential as a treatment for memory impairments.

Expanding applications of allogeneic platelets, platelet lysates, and platelet extracellular vesicles in cell therapy, regenerative medicine, and targeted drug delivery

Platelets are small anucleated blood cells primarily known for their vital hemostatic role. Allogeneic platelet concentrates (PCs) collected from healthy donors are an essential cellular product transfused by hospitals to control or prevent bleeding in patients affected by thrombocytopenia or platelet dysfunctions. Platelets fulfill additional essential functions in innate and adaptive immunity and inflammation, as well as in wound-healing and tissue-repair mechanisms. Platelets contain mitochondria, lysosomes, dense granules, and alpha-granules, which collectively are a remarkable reservoir of multiple trophic factors, enzymes, and signaling molecules. In addition, platelets are prone to release in the blood circulation a unique set of extracellular vesicles (p-EVs), which carry a rich biomolecular cargo influential in cell-cell communications. The exceptional functional roles played by platelets and p-EVs explain the recent interest in exploring the use of allogeneic PCs as source material to develop new biotherapies that could address needs in cell therapy, regenerative medicine, and targeted drug delivery. Pooled human platelet lysates (HPLs) can be produced from allogeneic PCs that have reached their expiration date and are no longer suitable for transfusion but remain valuable source materials for other applications. These HPLs can substitute for fetal bovine serum as a clinical grade xeno-free supplement of growth media used in the in vitro expansion of human cells for transplantation purposes. The use of expired allogeneic platelet concentrates has opened the way for small-pool or large-pool allogeneic HPLs and HPL-derived p-EVs as biotherapy for ocular surface disorders, wound care and, potentially, neurodegenerative diseases, osteoarthritis, and others. Additionally, allogeneic platelets are now seen as a readily available source of cells and EVs that can be exploited for targeted drug delivery vehicles. This article aims to offer an in-depth update on emerging translational applications of allogeneic platelet biotherapies while also highlighting their advantages and limitations as a clinical modality in regenerative medicine and cell therapies.

Platelet-derived exerkine CXCL4/platelet factor 4 rejuvenates hippocampal neurogenesis and restores cognitive function in aged mice

The beneficial effects of physical activity on brain ageing are well recognised, with exerkines, factors that are secreted into the circulation in response to exercise, emerging as likely mediators of this response. However, the source and identity of these exerkines remain unclear. Here we provide evidence that an anti-geronic exerkine is secreted by platelets. We show that platelets are activated by exercise and are required for the exercise-induced increase in hippocampal precursor cell proliferation in aged mice. We also demonstrate that increasing the systemic levels of the platelet-derived exerkine CXCL4/platelet factor 4 (PF4) ameliorates age-related regenerative and cognitive impairments in a hippocampal neurogenesis-dependent manner. Together these findings highlight the role of platelets in mediating the rejuvenating effects of exercise during physiological brain ageing.

Advances in extracellular vesicle functionalization strategies for tissue regeneration

Extracellular vesicles (EVs) are nano-scale vesicles derived by cell secretion with unique advantages such as promoting cell proliferation, anti-inflammation, promoting blood vessels and regulating cell differentiation, which benefit their wide applications in regenerative medicine. However, the in vivo therapeutic effect of EVs still greatly restricted by several obstacles, including the off-targetability, rapid blood clearance, and undesired release. To address these issues, biomedical engineering techniques are vastly explored. This review summarizes different strategies to enhance EV functions from the perspective of drug loading, modification, and combination of biomaterials, and emphatically introduces the latest developments of functionalized EV-loaded biomaterials in different diseases, including cardio-vascular system diseases, osteochondral disorders, wound healing, nerve injuries. Challenges and future directions of EVs are also discussed.

Platelet lysate promotes hair growth: In vitro and in vivo mechanism and randomized, controlled trial

BACKGROUND

Platelet lysate (PL), a novel platelet derivative, has been widely used in regenerative medicine and is a potential therapy for improving hair growth. It is necessary to fully clarify the potential mechanism and evaluate preliminary clinical effect of PL on hair growth.

METHODS

We used the C57BL/6 model, organ-cultured hair follicles, and RNA-seq analysis to explore the mechanisms of PL regulating hair growth. Then, we performed a randomized, controlled, double-blind study of 107 AGA patients to verify the therapeutic efficacy of PL.

RESULTS

The results confirmed that PL improved hair growth and accelerated hair cycling in mice. Organ-cultured hair follicle evaluation confirmed that PL prolonged anagen remarkably and down-regulated IL-6, C-FOS, and p-STAT5a. Clinically, diameter, hair counts, absolute anagen counts and changes from baseline in the PL group showed a significant improvement at 6 months.

CONCLUSIONS

We elucidated the specific molecular mechanism of PL action on hair growth and proved equal changes in hair follicle performance after PL vs PRP in AGA patients. This study provided novel knowledge of PL, making it ideal for AGA.

The Pathophysiological Role of Platelet-Derived Extracellular Vesicles

Platelets are very abundant in the blood, where they play a role in hemostasis, inflammation, and immunity. When activated, platelets undergo a conformational change that allows the release of numerous effector molecules as well as the production of extracellular vesicles, which are circulating submicron vesicles (10 to 1,000 nm in diameter) released into the extracellular space. Extracellular vesicles are formed by the budding of platelet and they carry some of its contents, including nucleic acids, surface proteins, and organelles. While platelets cannot cross tissue barriers, platelet-derived extracellular vesicles can enter the lymph, bone marrow, and synovial fluid. This allows the transfer of diverse contents carried by these platelet-derived vesicles to cell recipients and organs inaccessible to platelets where they can perform many functions. This review highlights the importance of these platelet-derived extracellular vesicles under different physiological and pathophysiological conditions.

The effect of platelet lysate on mouse ovarian structure, function and epigenetic modifications after autotransplantation

RESEARCH QUESTION

What are the effects of platelet lysate on structure, function and epigenetic modifications of heterotopically transplanted mouse ovarian tissues?

DESIGN

Mice were divided into three groups (n = 17 per group): control (mice with no ovariectomy, grafting or treatment), autograft and autograft plus platelet lysate (3 ml/kg at the graft sites). Inflammatory markers, serum malondialdehyde (MDA) concentration and total antioxidant capacity were assessed on day 7 after transplantation. Twenty-eight days after transplantation, stereological and hormonal analyses were conducted. Chromatin immunoprecipitation and quantitative real-time polymerase chain reaction were also used to quantify the epigenetic modifications of maturation genes, parallel to their expression.

RESULTS

The total volume of the ovary, cortex and medulla, and the number of different types of follicles, the concentration of interleukin (IL)-10, progesterone and oestradiol and total antioxidant capacity significantly decreased in the autograft group compared with the control group (P < 0.001); these parameters significantly increased in the autograft plus platelet lysate group compared with the autograft group (P < 0.001). The concentrations of tumour necrosis factor alpha, IL-6 and MDA increased significantly in the autograft group compared with the control group (P < 0.001); in the autograft plus platelet lysate group, these parameters significantly decreased compared with the autograft group (P < 0.001). In the autograft plus platelet lysate group, the expression levels of Gdf-9 (P < 0.0021), Igf-1 (P < 0.0048) and Igf-2 (P < 0.0063) genes also increased along with a lower incorporation of MeCP2 in the promoter regions (P < 0.001) compared with the autograft group.

CONCLUSIONS

Platelet lysate can contribute to follicular survival by improving folliculogenesis and increasing the expression of oocyte maturation genes.

Platelets, Protean Cells with All-Around Functions and Multifaceted Pharmacological Applications

Platelets, traditionally known for their roles in hemostasis and coagulation, are the most prevalent blood component after erythrocytes (150,000-400,000 platelets/μL in healthy humans). However, only 10,000 platelets/μL are needed for vessel wall repair and wound healing. Increased knowledge of the platelet's role in hemostasis has led to many advances in understanding that they are crucial mediators in many other physiological processes, such as innate and adaptive immunity. Due to their multiple functions, platelet dysfunction is involved not only in thrombosis, mediating myocardial infarction, stroke, and venous thromboembolism, but also in several other disorders, such as tumors, autoimmune diseases, and neurodegenerative diseases. On the other hand, thanks to their multiple functions, nowadays platelets are therapeutic targets in different pathologies, in addition to atherothrombotic diseases; they can be used as an innovative drug delivery system, and their derivatives, such as platelet lysates and platelet extracellular vesicles (pEVs), can be useful in regenerative medicine and many other fields. The protean role of platelets, from the name of Proteus, a Greek mythological divinity who could take on different shapes or aspects, is precisely the focus of this review.

Neuroprotective activity of a virus-safe nanofiltered human platelet lysate depleted of extracellular vesicles in Parkinson's disease and traumatic brain injury models

Brain administration of human platelet lysates (HPL) is a potential emerging biotherapy of neurodegenerative and traumatic diseases of the central nervous system. HPLs being prepared from pooled platelet concentrates, thereby increasing viral risks, manufacturing processes should incorporate robust virus-reduction treatments. We evaluated a 19 ± 2-nm virus removal nanofiltration process using hydrophilic regenerated cellulose hollow fibers on the properties of a neuroprotective heat-treated HPL (HPPL). Spiking experiments demonstrated >5.30 log removal of 20-22-nm non-enveloped minute virus of mice-mock particles using an immuno-quantitative polymerase chain reaction assay. The nanofiltered HPPL (NHPPL) contained a range of neurotrophic factors like HPPL. There was >2 log removal of extracellular vesicles (EVs), associated with decreased expression of pro-thrombogenic phosphatidylserine and procoagulant activity. LC-MS/MS proteomics showed that ca. 80% of HPPL proteins, including neurotrophins, cytokines, and antioxidants, were still found in NHPPL, whereas proteins associated with some infections and cancer-associated pathways, pro-coagulation and EVs, were removed. NHPPL maintained intact neuroprotective activity in Lund human mesencephalic dopaminergic neuron model of Parkinson's disease (PD), stimulated the differentiation of SH-SY5Y neuronal cells and showed preserved anti-inflammatory function upon intranasal administration in a mouse model of traumatic brain injury (TBI). Therefore, nanofiltration of HPL is feasible, lowers the viral, prothrombotic and procoagulant risks, and preserves the neuroprotective and anti-inflammatory properties in neuronal pre-clinical models of PD and TBI.

The multifaceted role of platelets in mediating brain function

Platelets, the small, anucleate blood cells that originate from megakaryocytes in the bone marrow, are typically associated with coagulation. However, it is now apparent that platelets are more multifaceted than originally thought, with their function extending beyond their traditional role in hemostasis to acting as important mediators of brain function. In this review, we outline the broad repertoire of platelet function in the central nervous system, focusing on the similarities between platelets and neurons. We also summarize the role that platelets play in the pathophysiology of various neurological diseases, with a particular focus on neuroinflammation and neurodegeneration. Finally, we highlight the exciting prospect of harnessing the unique features of the platelet proteome and extracellular vesicles, which are rich in neurotrophic, antioxidative, and antiinflammatory factors, for the development of novel neuroprotective and neuroregenerative interventions to treat various neurodegenerative and traumatic pathologies.

In vitro evaluation of platelet extracellular vesicles (PEVs) for corneal endothelial regeneration

Corneal endothelial cells (CECs) slowly decrease in number with increasing age, which is a clinical issue as these cells have very limited regenerative ability. Therapeutic platelet biomaterials are increasingly used in regenerative medicine and cell therapy because of their safety, cost-effective manufacture, and global availability from collected platelet concentrates (PCs). Platelet extracellular vesicles (PEVs) are a complex mixture of potent bioactive vesicles rich in molecules believed to be instrumental in tissue repair and regeneration. In this study we investigated the feasibility of using a PEVs preparation as an innovative regenerative biotherapy for corneal endothelial dysfunction. The PEVs were isolated from clinical-grade human PC supernatants by 20,000 × g ultracentrifugation and resuspension. PEVs exhibited a regular, fairly rounded shape, with an average size of <200 nm and were present at a concentration of approximately 10¹¹ /mL. PEVs expressed cluster of differentiation 41 (CD41) and CD61, characteristic platelets membrane markers, and CD9 and CD63. ELISA and LC-MS/MS proteomic analyses revealed that the PEVs contained mixtures of growth factors and multiple other trophic factors, as well as proteins related to extracellular exosomes with functional activities associated with cell cadherin and adherens pathways. CECs treated with PEVs showed increased viability, an enhanced wound-healing rate, stronger proliferation markers, and an improved adhesion rate. PEVs did not exert cellular toxicity as evidenced by the maintenance of cellular morphology and preservation of corneal endothelial proteins. These findings clearly support further investigations of PEV biomaterials in animal models for translation as a new CEC regeneration biotherapy.

Can the administration of platelet lysates to the brain help treat neurological disorders?

Neurodegenerative disorders of the central nervous system (CNS) and brain traumatic insults are characterized by complex overlapping pathophysiological alterations encompassing neuroinflammation, alterations of synaptic functions, oxidative stress, and progressive neurodegeneration that eventually lead to irreversible motor and cognitive dysfunctions. A single pharmacological approach is unlikely to provide a complementary set of molecular therapeutic actions suitable to resolve these complex pathologies. Recent preclinical data are providing evidence-based scientific rationales to support biotherapies based on administering neurotrophic factors and extracellular vesicles present in the lysates of human platelets collected from healthy donors to the brain. Here, we present the most recent findings on the composition of the platelet proteome that can activate complementary signaling pathways in vivo to trigger neuroprotection, synapse protection, anti-inflammation, antioxidation, and neurorestoration. We also report experimental data where the administration of human platelet lysates (HPL) was safe and resulted in beneficial neuroprotective effects in established rodent models of neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, traumatic brain injury, and stroke. Platelet-based biotherapies, prepared from collected platelet concentrates (PC), are emerging as a novel pragmatic and accessible translational therapeutic strategy for treating neurological diseases. Based on this assumption, we further elaborated on various clinical, manufacturing, and regulatory issues that need to be addressed to ensure the ethical supply, quality, and safety of HPL preparations for treating neurodegenerative and traumatic pathologies of the CNS. HPL made from PC may become a unique approach for scientifically based treatments of neurological disorders readily accessible in low-, middle-, and high-income countries.

Whole and fractionated human platelet lysate biomaterials-based biotherapy induces strong neuroprotection in experimental models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease of motor neurons leading to death within 3 years and without a curative treatment. Neurotrophic growth factors (NTFs) are pivotal for cell survival. A reason for the lack of patient efficacy with single recombinant NTF brain infusion is likely to be due to the synergistic neuroprotective action of multiple NTFs on a diverse set of signaling pathways. Fractionated (protein size <50, <30, <10, <3 kDa) heat-treated human platelet lysate (HHPL) preparations were adapted for use in brain tissue with the aim of demonstrating therapeutic value in ALS models and further elucidation of the mechanisms of action. In neuronal culture all fractions induced Akt-dependent neuroprotection as well as a strong anti-apoptotic and anti-ferroptotic action. In the <3 kDa fraction anti-ferroptotic properties were shown to be GPX4 dependent highlighting a role for other platelet elements associated with NTFs. In the SOD1^G86R mouse model, lifespan was strongly increased by intracerebroventricular delivery of HHPL or by intranasal administration of <3 kDa fraction. Our results suggest that the platelet lysate biomaterials are neuroprotective in ALS. Further studies would now validate theragnostic biomarker on its antiferroptotic action, for further clinical development.

Characterization and Chromatographic Isolation of Platelet Extracellular Vesicles from Human Platelet Lysates for Applications in Neuroregenerative Medicine

Human platelet lysates (HPLs) made from clinical-grade platelet concentrates are currently evaluated in the preclinical models of Parkinson's disease, Alzheimer's disease, traumatic brain injury, and others, as a new polyvalent neuroprotective biotherapy of the central nervous system. However, the presence and content of extracellular vesicles (EVs) in HPLs and their potential contribution to the neuroprotective and neurorestorative activities of HPLs are still unknown. We, therefore, characterized the EVs present in four different HPL preparations and after purification by size-exclusion chromatography. We then tested the effect of the isolated EVs on neuronal cell repair. We identified that all four HPLs contained a high and similar amount of EVs (10¹¹ to 10¹²/mL) with a mean size ranging from ca. 50 to 300 nm and a negative zeta potential as determined by nanoparticle tracking analysis and dynamic light scattering. Western blot analysis revealed that the EVs present in HPLs expressed the clusters of differentiation 41 (CD41) and 61 (CD61) characteristic of platelets. These EVs were efficiently isolated from HPL proteins by Sepharose CL-2B size-exclusion column chromatography as confirmed by total protein determination and protein profile by sodium dodecyl sulfate polyacrylamide gel electrophoresis, with 73-85% recovery and maintenance of their size, negative zeta potential, and CD41 and CD61 expression. Interestingly, the EVs purified from the four HPLs exhibited a differential capacity to promote cell growth and migration in a wound-healing assay using SH-SY5Y neuronal cells, and one EV preparation stimulated network formation in primary neuronal cultures. These data indicated that the EVs present in HPLs have different neuroregenerative capacities and that some EV preparations may have interesting applications as a stand-alone therapy for usage in neuroregenerative medicine.

Identification of Novel Biomarkers in Platelets for Diagnosing Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disease affecting the elderly, but there is no blood test for PD diagnosis in the clinic currently. This study aimed to explore promising biomarkers in platelets (PLTs) for PD diagnosis.

METHODS

PLTs were isolated from whole blood samples of PD patients and healthy controls (HCs), and RNA was extracted for sequencing. RNA-seq was performed on the Illumina HiSeq platform.

RESULTS

A total of 2,221 genes with differential transcript levels (GDTLs) were identified between PD patients and HCs, 1,041 of which are upregulated genes and 1,180 of which are downregulated genes. WASH5P was the most upregulated gene and AC114491.1 was the most downregulated gene. Among the top 12 most relevant genes, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), eukaryotic elongation factor 1A (EEF1A1), and cathepsin S (CTSS) were reported to be associated with PD. Furthermore, gene ontology analysis showed that the most significant term in biological processes was neutrophil degranulation; the most enriched term in cellular components was cytoplasmic vesicle lumen; and tumor necrosis factor receptor superfamily binding was the most significant term in molecular functions. In the Kyoto Encyclopedia of Genes and Genomes enrichment analysis, inflammation-related pathway accounts for the majority.

CONCLUSION

Our findings demonstrated WASH5P, MALAT1, EEF1A1, and CTSS may be promising biomarkers in PD, which may contribute to improving the effectiveness and accuracy of diagnosis for PD in the future.

Human platelet lysate biotherapy for traumatic brain injury: preclinical assessment

Traumatic brain injury (TBI) leads to major brain anatomopathological damages underlined by neuroinflammation, oxidative stress and progressive neurodegeneration, ultimately leading to motor and cognitive deterioration. The multiple pathological events resulting from TBI can be addressed not by a single therapeutic approach, but rather by a synergistic biotherapy capable of activating a complementary set of signalling pathways and providing synergistic neuroprotective, anti-inflammatory, antioxidative, and neurorestorative activities. Human platelet lysate might fulfil these requirements as it is composed of a plethora of biomolecules readily accessible as a TBI biotherapy. In the present study, we tested the therapeutic potential of human platelet lysate using in vitro and in vivo models of TBI. We first prepared and characterized platelet lysate from clinical-grade human platelet concentrates. Platelets were pelletized, lysed by three freeze-thaw cycles, and centrifuged. The supernatant was purified by 56°C 30 min heat treatment and spun to obtain the heat-treated platelet pellet lysate that was characterized by ELISA and proteomic analyses. Two mouse models were used to investigate platelet lysate neuroprotective potential. The injury was induced by an in-house manual controlled scratching of the animals' cortex or by controlled cortical impact injury. The platelet lysate treatment was performed by topical application of 60 µl in the lesioned area, followed by daily 60 µl intranasal administration from Day 1 to 6 post-injury. Platelet lysate proteomics identified over 1000 proteins including growth factors, neurotrophins, and antioxidants. ELISA detected several neurotrophic and angiogenic factors at ∼1-50 ng/ml levels. We demonstrate, using two mouse models of TBI, that topical application and intranasal platelet lysate consistently improved mouse motor function in the beam and rotarod tests, mitigated cortical neuroinflammation, and oxidative stress in the injury area, as revealed by downregulation of pro-inflammatory genes and the reduction in reactive oxygen species levels. Moreover, platelet lysate treatment reduced the loss of cortical synaptic proteins. Unbiased proteomic analyses revealed that heat-treated platelet pellet lysate reversed several pathways promoted by both controlled cortical impact and cortical brain scratch and related to transport, postsynaptic density, mitochondria or lipid metabolism. The present data strongly support, for the first time, that human platelet lysate is a reliable and effective therapeutic source of neurorestorative factors. Therefore, brain administration of platelet lysate is a therapeutical strategy that deserves serious and urgent consideration for universal brain trauma treatment.

A purified human platelet pellet lysate rich in neurotrophic factors and antioxidants repairs and protects corneal endothelial cells from oxidative stress

Human platelet lysate (HPL) is a complex mixture of potent bioactive molecules instrumental in tissue repair and regeneration. Due to their remarkable safety, cost-effective production, and availability at global level from collected platelet concentrates, HPLs can become a powerful biotherapy for various therapeutic applications, if standardized and carefully validated through pre-clinical and clinical studies. In this work, the possibility to use a tailor-made HPL as a corneal transplant alternative to treat the gradual decrease in the number of corneal endothelial cells (CECs) associated with aging, was evaluated. The HPL preparation was thoroughly characterized using various proteomics tools that revealed a remarkable richness in multiple growth factors and antioxidants. Treatment of B4G12 and BCE C/D-1b CECs with the HPL increased their viability, enhanced the wound closure rate, and maintained cell growth and typical hexagonal morphology. Besides, this HPL significantly protected against tert-butyl hydroperoxide (TBHP)-induced oxidative stress as evidenced by increasing CEC viability, decreased cell death and reactive oxygen species formation, and enhanced antioxidant capacity. Proteomics analysis of treated CECs confirmed that HPL treatment triggered the corneal healing pathway and enhanced oxidative stress. These data strongly support further pre-clinical evaluation of this tailor-made HPL as a novel CEC regeneration biotherapy. HPL treatment may eventually represent a pragmatic and cost-effective alternative to corneal transplant to treat damages of the corneal endothelium which is a major cause of blindness worldwide.

Removal of minute virus of mice-mock virus particles by nanofiltration of culture growth medium supplemented with 10% human platelet lysate

BACKGROUND AIMS

Platelet concentrates (PCs) are pooled to prepare human platelet lysate (HPL) supplements of growth media to expand primary human cells for transplantation; this increases the risk of contamination by known, emerging, and unknown viruses. This possibility should be of concern because viral contamination of cell cultures is difficult to detect and may have detrimental consequences for recipients of cell therapies. Viral reduction treatments of chemically defined growth media have been proposed, but they are not applicable when media contain protein supplements currently needed to expand primary cell cultures. Recently, we successfully developed a Planova 35NPlanova 20N nanofiltration sequence of growth media supplemented with two types of HPL. The nanofiltered medium was found to be suitable for mesenchymal Stromal cell (MSC) expansion.

METHODS

Herein, we report viral clearance achieved by this nanofiltration process used for assessing a new experimental model using non-infectious minute virus of mice-mock virus particle (MVM-MVP) and its quantification by an immunoqPCR. Then, high doses of MVM-MVP (1012 MVPs/mL) were spiked to obtain a final concentration of 1010 MVPs/mL in Planova 35N-nanofiltered growth medium supplemented with both types of HPLs [serum converted platelet lysate SCPL) and intercept human platelet lysate (I-HPL)] at 10% (v/v) and then filtering through Planova 20N.

RESULTS

No substantial interference of growth medium matrices by the immune-qPCR assay was first verified. Log reduction values (LRVs) were ≥ 5.43 and ≥ 5.36 respectively, SCPL and I-HPL media. MVM-MVPs were also undetectable by dynamic light scattering and transmission electron microscopy.

CONCLUSIONS

The nanofiltration of growth media supplemented with 10% HPL provides robust removal of small nonenveloped viruses, and is an option to improve the safety of therapeutic cells expanded using HPL supplements.

PRP in wound healing applications

Platelets play a crucial role in hemostasis, tissue regeneration and host defense. Based on these settings, platelet-rich plasma (PRP) and its derivatives are therapeutically used to promote wound healing in several scenarios. This review summarizes the biological mechanisms underlying the most traditional as well as innovative applications of PRP in wound healing. These mechanisms involve the combined action of platelet-derived growth factors and cytokines, together with the role of plasma-derived fibrillar, antioxidant and homeostatic factors. In addition, regenerative treatments with PRP consist of personalized and non-standardized methods. Thus, the quality of PRP varies depending on endogenous factors (e.g., age; gender; concomitant medication; disease-associated systemic factors; nutrition) and exogenous factors (anticoagulants and cellular composition). This review also analyses whether these factors affect the biological mechanisms of PRP in wound healing applications.

Extensive characterization of the composition and functional activities of five preparations of human platelet lysates for dedicated clinical uses

Human platelet lysates (HPLs), rich in various growth factors and cell growth-promoting molecules, encompass a new range of blood products that are being used for regenerative medicine, cell therapies, and tissue engineering. Well-characterized dedicated preparations, tailor-made to best fit specific therapeutic applications, are needed for optimal clinical efficacy and safety. Here, five types of HPL were prepared from the same platelet concentrates and extensively characterized to determine and compare their proteins, growth factors, cytokines, biochemical profiles, thrombin-generating capacities, thrombin-associated proteolytic activities, phospholipid-associated procoagulant potential, contents of extracellular vesicles expressing phosphatidylserine and tissue factor, and antioxidative properties. Our results revealed that all five HPL preparations contained detectable supraphysiological levels, in the ca. 0.1 ~ 350-ng/ml range, of all growth factors assessed, except insulin-like growth factor-1 detected only in HPL containing plasma. There were significant differences observed among these HPLs in total protein content, fibrinogen, complement components C3 and C4, albumin, and immunoglobulin G, and, most importantly, in their functional coagulant and procoagulant activities and antioxidative capacities. Our data revealed that the biochemical and functional properties of HPL preparations greatly vary depending upon their mode of production, with potential impacts on the safety and efficacy for certain clinical indications. Modes of preparation of HPLs should be carefully designed, and the product properties carefully evaluated based on the intended therapeutic use to ensure optimal clinical outcomes.

Prospective Therapeutic Applications of Platelet Extracellular Vesicles

There is much interest in the use of extracellular vesicles (EVs) as a subcellular therapy for regenerative medicine and drug delivery. Blood-borne platelets represent a source of therapeutic EVs that is so far largely unexplored. Advantages of platelets as a cellular source of EVs include their established clinical value, regulated collection procedures, availability in a concentrated form, propensity to generate EVs, and unique composition and tissue-targeting capacity. This review analyzes the unique potential of platelet-derived (p-) EVs as therapeutic modalities and presents their inherent translational advantages for hemostasis, for regenerative medicine, and as drug-delivery vehicles.

Platelets in Neurodegenerative Conditions-Friend or Foe?

It is now apparent that platelet function is more diverse than originally thought, shifting the view of platelets from blood cells involved in hemostasis and wound healing to major contributors to numerous regulatory processes across different tissues. Given their intriguing ability to store, produce and release distinct subsets of bioactive molecules, including intercellular signaling molecules and neurotransmitters, platelets may play an important role in orchestrating healthy brain function. Conversely, a number of neurodegenerative conditions have recently been associated with platelet dysfunction, further highlighting the tissue-independent role of these cells. In this review we summarize the requirements for platelet-neural cell communication with a focus on neurodegenerative diseases, and discuss the therapeutic potential of healthy platelets and the proteins which they release to counteract these conditions.

Heat-treated human platelet pellet lysate modulates microglia activation, favors wound healing and promotes neuronal differentiation in vitro

The neurorestorative efficacy of human platelet lysates in neurodegenerative disorders is still under investigation. Platelets prepared from standard and pathogen reduced platelet concentrates were pelletized, washed, concentrated, and subjected to freeze-thawing. The lysate was heated to 56°C for 30 min and characterized. Toxicity was evaluated using SH-SY5Y neuroblastoma, BV-2 microglial, and EA-hy926 endothelial cells. Inflammatory activity was tested by examining tumor necrosis factor (TNF) and cyclooxygenase (COX)-2 expressions by BV-2 microglia with or without stimulation by lipopolysaccharides (LPS). The capacity to stimulate wound healing was evaluated by a scratch assay, and the capacity to differentiate SH-SY5Y into neurons was also examined. Platelet lysates contained a range of neurotrophins. They were not toxic to SH-SY5Y, EA-hy926, or BV-2 cells, did not induce the expression of TNF or COX-2 inflammatory markers by BV-2 microglia, and decreased inflammation after LPS stimulation. They stimulated the wound closure in the scratch assay and induced SH-SY5Y differentiation as revealed by the increased length of neurites as well as β3-tubulin and neurofilament staining. These data confirm the therapeutic potential of platelet lysates in the treatment of disorders of the central nervous system and support further evaluation as novel neurorestorative biotherapy in preclinical models.

Viral safety of human platelet lysate for cell therapy and regenerative medicine: Moving forward, yes, but without forgetting the past

Growth factor-rich pooled human platelet lysate (HPL), made from human platelet concentrates, is one new blood-derived bioproduct that is attracting justified interest as a xeno-free supplement of growth media for human cell propagation for cell therapy. HPL can also find potentially relevant applications in the field of regenerative medicine. Therefore, the therapeutic applications of HPL go far beyond the standard clinical applications of the traditional blood products typically used in patients suffering from life-threatening congenital or acquired deficiencies in cellular components or proteins due to severe genetic diseases or trauma. A wider population of patients, suffering from various pathologies than has traditionally been the case, is thus, now susceptible to receiving a human blood-derived product. These patients would, therefore, be exposed to the possible, but avoidable, side effects of blood products, including transfusion-transmitted infections, most specifically virus transmissions. Unfortunately, not all manufacturers, suppliers, and users of HPL may have a strong background in the blood product industry. As such, they may not be fully aware of the various building blocks that should contribute to the viral safety of HPL as is already the case for any licensed blood products. The purpose of this manuscript is to reemphasize all the measures, including in regulatory aspects, capable of assuring that HPL exhibits a sufficient pathogen safety margin, especially when made from large pools of human platelet concentrates. It is vital to remember the past to avoid that the mistakes, which happened 30 to 40 years ago and led to the contamination of many blood recipients, be repeated due to negligence or ignorance of the facts.

The neuroprotective activity of heat-treated human platelet lysate biomaterials manufactured from outdated pathogen-reduced (amotosalen/UVA) platelet concentrates

Background

Effective neurorestorative therapies of neurodegenerative diseases must be developed. There is increasing interest in using human platelet lysates, rich in neurotrophic factors, as novel disease-modifying strategy of neurodegeneration. To ensure virus safety, pathogen reduction treatments should be incorporated in the preparation process of the platelet concentrates used as source material. We therefore investigated whether platelet concentrates (PC) pathogen-inactivated using a licensed photo-inactivation treatment combining photosensitive psoralen (amotosalen) and UVA irradiation (Intercept) can serve as source material to prepare platelet lysates with preserved neuroprotective activity in Parkinson’s disease models.

Methods

Intercept treated-PCs were centrifuged, when reaching expiry day (7 days after collection), to remove plasma and platelet additive solution. The platelet pellet was re-suspended and concentrated in phosphate buffer saline, subjected to 3 freeze-thaw cycles (− 80 °C/37 °C) then centrifuged to remove cell debris. The supernatant was recovered and further purified, or not, by heat-treatment as in our previous investigations. The content in proteins and neurotrophic factors was determined and the toxicity and neuroprotective activity of the platelet lysates towards LUHMES cells or primary cortical/hippocampal neurons were assessed using ELISA, flow cytometry, cell viability and cytotoxicity assays and proteins analysis by Western blot.

Results

Platelet lysates contained the expected level of total proteins (ca. 7–14 mg/mL) and neurotrophic factors. Virally inactivated and heat-treated platelet lysates did not exert detectable toxic effects on neither Lund human mesencephalic dopaminergic LUHMES cell line nor primary neurons. When used at doses of 5 and 0.5%, they enhanced the expression of tyrosine hydroxylase and neuron-specific enolase in LUHMES cells and did not significantly impact synaptic protein expression in primary neurons, respectively. Furthermore, virally-inactivated platelet lysates tested were found to exert very strong neuroprotection effects on both LUHMES and primary neurons exposed to erastin, an inducer of ferroptosis cell death.

Conclusion

Outdated Intercept pathogen-reduced platelet concentrates can be used to prepare safe and highly neuroprotective human heat-treated platelet pellet lysates. These data open reassuring perspectives in the possibility to develop an effective biotherapy using virally-inactivated platelet lysates rich in functional neurotrophins for neuroregenerative medicine, and for further bio-industrial development. However, the data should be confirmed in animal models.

Graphical abstract

Platelets: The missing link between the blood and brain?

It is becoming increasingly clear that interactions between the peripheral immune system and the central nervous system are important in maintaining healthy brain function. Platelets are small blood cells traditionally known for their role in wound healing. However, platelets have recently been shown to exhibit many alternative functions. In this perspective, we summarize the repertoire of platelet functions, focusing on how these cells contribute to the maintenance of brain homeostasis and propose the mechanisms via which they could communicate with brain cells, including exosome and microparticle release and receptor interactions at local sites. In particular, we highlight the potential role that platelets play in maintaining brain plasticity via the modulation of new neuron generation from neural precursor cells, an interaction which could have important implications in the development of therapeutic interventions to promote cognitive function in aging and disease.

Past and Future of Neurotrophic Growth Factors Therapies in ALS: From Single Neurotrophic Growth Factor to Stem Cells and Human Platelet Lysates

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that typically results in death within 3–5 years after diagnosis. To date, there is no curative treatment and therefore an urgent unmet need of neuroprotective and/or neurorestorative treatments. Due to their spectrum of capacities in the central nervous system—e.g., development, plasticity, maintenance, neurogenesis—neurotrophic growth factors (NTF) have been exploited for therapeutic strategies in ALS for decades. In this review we present the initial strategy of using single NTF by different routes of administration to the use of stem cells transplantation to express a multiple NTFs-rich secretome to finally focus on a new biotherapy based on the human platelet lysates, the natural healing system containing a mix of pleitropic NTF and having immunomodulatory function. This review highlights that this latter treatment may be crucial to power the neuroprotection and/or neurorestoration therapy requested in this devastating disease.

Novel therapeutic approaches in utilizing platelet lysate in regenerative medicine: Are we ready for clinical use?

Hemoderivative materials are used to treat different diseases. These derivatives include platelet-rich plasma, serum, platelet gel, and platelet lysate (PL). Among them, PL contains more growth factors than the others and its production is inexpensive and easy. PL is one of the proper sources of platelet release factors. It is used in cells growth and proliferation and is a good alternative to fetal bovine serum. In recent years, the clinical use of PL has gained more appeal by scientists. PL is a solution saturated by growth factors, proteins, cytokines, and chemokines and is administered to treat different diseases such as wound healing, bone regeneration, alopecia, oral mucositis, radicular pain, osteoarthritis, and ocular diseases. In addition, it can be used in cell culture for cell therapy and tissue transplantation purposes. Platelet-derived growth factor, fibroblast growth factor, insulin-like growth factor, transforming growth factor β, and vascular endothelial growth factor are key PL growth factors playing a major role in cell proliferation, wound healing, and angiogenesis. In this paper, we scrutinized recent advances in using PL and PL-derived growth factors to treat diseases and in regenerative medicine, and the ability to replace PL with other hemoderivative materials.

Ascorbic acid-modified brain-specific liposomes drug delivery system with "lock-in" function

In this study, a novel brain targeting ascorbic acid (AA) derivative with "lock-in" function was designed and synthesized as a liposome ligand to prepare novel liposomes to achieve the effective delivery of drug formulations to brain via glucose transporter 1 (GLUT₁) and the Na⁺-dependent vitamin C transporter (SVCT₂). The liposome was prepared and characterized in terms of the particle size, zeta potential, encapsulation efficiency, release profile, stability, hemolysis and cell cytotoxicity. The preliminary evaluation in vivo demonstrated that the AA-thiamine disulfide system (TDS)-coated liposome had an improved targeting ability and significantly increased the brain concentration of docetaxel (DTX) as compared to the naked docetaxel, the non-coated and the AA-coated liposomes. The relative uptake efficiency and concentration efficiency were enhanced by 3.24- and 5.62-fold compared to that of the naked docetaxel, respectively. Both distribution data and pharmacokinetic parameters suggested that the ascorbic acid thiamine disulfide delivery system was a promising carrier to enhance central nervous system (CNS) drug's delivery ability into brain.

Four types of human platelet lysate, including one virally inactivated by solvent-detergent, can be used to propagate Wharton jelly mesenchymal stromal cells

There is accumulating experimental evidence that human platelet lysate (HPL) made from platelet concentrates can replace fetal bovine serum (FBS) as a xeno-free clinical-grade supplement of growth media to expand mesenchymal stromal cells (MSCs). However, uncertainties exist in regard to impacts that various manufacturing methods of HPL can exert on the expansion and differentiation capacity of MSCs. In particular, there is a need to evaluate the possibility of implementing virus-inactivation treatment during HPL production to ensure optimal safety of industrial HPL pools. Expired human platelet concentrates from four different donors were pooled and subjected to freeze-thaw cycles (-80/+37 °C), followed or not by serum-conversion by calcium chloride, heat-treatment at 56 °C for 30 min, or solvent-detergent (S/D) virus inactivation. The concentrations of total proteins, growth factors and fibrinogen, and the chemical compositions of the HPLs were characterized. The impact of HPL supplementation on the cell morphology, doubling time, immunophenotype and trilineage differentiation capacity of Wharton jelly MSCs (WJMSCs) were compared over five passages, using FBS as a control and normalizing the protein content. Data showed that WJMSCs expanded equally well, exhibited a typical fibroblast morphology, had short doubling times, maintained their immunophenotypes, and differentiated into chondrocyte, osteocyte, and adipocyte lineages in all HPL-supplemented media, all of which were more effective than FBS. In conclusion, we found minimal detectable impact of the HPL manufacturing process, including S/D virus inactivation, on the suitability of expanding WJMSCs in vitro.

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.

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.