Clinical-grade quality platelet-rich plasma releasate (PRP-R/SRGF) from CaCl2 -activated platelet concentrates promoted expansion of mesenchymal stromal cells

Ex vivo expansion in a clinical grade medium, containing growth factors from human platelets, enhances migration capacity of adipose stem cells

Introduction

Adipose tissue mesenchymal stem/stromal cells (ASC) can be used as advanced therapy medicinal product in regenerative and cancer medicine. We previously demonstrated Supernatant Rich in Growth Factors (SRGF) can replace fetal bovine serum (FBS) to expand ASC by a clinical grade compliant protocol. The therapeutic potential of ASC is based also on their homing capacity toward inflammatory/cancer sites: oriented cell migration is a fundamental process in this scenario. We investigated the impact of SRGF on ASC migration properties.

Methods

The motility/migration potential of ASC expanded in 5% SRGF was analyzed, in comparison to 10% FBS, by standard wound healing, bidimensional chemotaxis and transwell assays, and by millifluidic transwell tests. Mechanisms involved in the migration process were investigated by transient protein overexpression.

Results

In comparison to standard 10% FBS, supplementation of the cell culture medium with 5% SRGF, strongly increased migration properties of ASC along the chemotactic gradient and toward cancer cell derived soluble factors, both in static and millifluidic conditions. We showed that, independently from applied migratory stimulus, SRGF expanded ASC were characterized by far lower expression of α-smooth muscle actin (αSMA), a protein involved in the cell migration machinery. Overexpression of αSMA induced a significant and marked decrease in migration capacity of SRGF expanded ASC.

Discussion

In conclusion, 5% SRGF addition in the cell culture medium increases the migration potential of ASC, reasonably through appropriate downregulation of αSMA. Thus, SRGF could potentially improve the therapeutic impact of ASC, both as modulators of the immune microenviroment or as targeted drug delivery vehicles in oncology.

Action of Platelet-Rich Plasma on In Vitro Cellular Bioactivity: More than Platelets

Platelet-rich plasma (PRP) is a biological therapy in which one of the mechanisms of action is the stimulation of biological processes such as cell proliferation. The size of PRP’s effect depends on multiple factors, one of the most important being the composition of PRP. The aim of this study was to analyze the relationship between cell proliferation and the levels of certain growth factors (IGF-1, HGF, PDGF, TGF-β and VEG) in PRP. First, the composition and effect on cell proliferation of PRP versus platelet-poor plasma (PPP) were compared. Subsequently, the correlation between each growth factor of PRP and cell proliferation was evaluated. Cell proliferation was higher in cells incubated with lysates derived from PRP compared to those cultured with lysates derived from PPP. In terms of composition, the levels of PDGF, TGF-β, and VEGF were significantly higher in PRP. When analyzing the PRP growth factors, IGF-1 was the only factor that correlated significantly with cell proliferation. Of those analyzed, the level of IGF-1 was the only one that did not correlate with platelet levels. The magnitude of PRP’s effect depends not only on platelet count but also on other platelet-independent molecules.

Current Status of PRP Manufacturing Requirements & European Regulatory Frameworks: Practical Tools for the Appropriate Implementation of PRP Therapies in Musculoskeletal Regenerative Medicine

Providing accurate and up-to-date practical tools enabling oversight of platelet-rich plasma (PRP) legislation and of the appropriate standards to be implemented for its manufacture and use in Europe is a demanding task. This is due to rapid medico-technological advancements, slowness and disparity in legislation updates and enforcement between member states, and many reported gray-zone practices, notably for autologous PRP use. The levels of risk associated with blood manipulation processes generally dictate the manufacturing requirements for PRP preparations, which have gradually shifted toward good manufacturing practices (GMP) for standardization and overall quality enhancement. This work firstly outlines Western European and Swiss legislation for PRP products/preparations, providing key simplified information and recommendations for medical doctors seeking to implement this biological-based therapy for safe use in hospital settings, clinics, or private offices. This work secondly shows the importance of PRP-based product manufacturing standardization, which subsequently enables sound clinical evaluation of therapeutic interventions. Although the applicable legal bases provide guidelines for GMP manufacturing infrastructure and basic process design, paramount importance is set on the definition of workflows, technical specifications, and key parameters for PRP preparation and delivery. Overall, the development of simple and robust technologies and processes for PRP preparation is critical for guaranteeing the high therapeutic quality of the intervention, in collaboration with qualified GMP manufacturing platforms. Importantly, this work aims to serve as a practical tool for clinicians based in Western Europe who are willing to appropriately (i.e., administratively and technically) implement autologous PRP treatments in musculoskeletal regenerative medicine workflows, to ensure they make informed and optimal regulatory or process-based decisions.

Variability in Platelet-Rich Plasma Preparations Used in Regenerative Medicine: A Comparative Analysis

Background

Platelet-rich plasma (PRP) and its derivatives are used in several aesthetic, dental, and musculoskeletal procedures. Their efficacy is primarily due to the release of various growth factors (GF), interleukins, cytokines, and white blood cells. However, the PRP preparation methods are highly variable, and studies lack consistency in reporting complete procedures to prepare PRP and characterize PRP and its derivatives. Also, all the tissue-specific (in vivo and in vitro) interactions and functional properties of the various derivatives/factors of the PRP have not been taken into consideration by any study so far. This creates a potential space for further standardization of the PRP preparation methods and customization of PRP/PRP derivatives targeted at tissue-specific/pathology specific requirements that would enable efficacious and widely acceptable usage of PRP as main therapy, rather than being used as adjuvant therapy. The main objective of our study was to investigate the variability in PRP preparation methods and to analyze their efficacy and reliability.

Method

This study considered articles published in the last 5 years, highlighting the variability in their PRP preparation methods and characterization of PRP. Following the PRISMA protocol, we selected 13 articles for the study. The selected articles were assessed using NHLBI quality assessment tool.

Results

We noted differences in (1) approaches to producing PRP, (2) extent of characterization of PRP, (3) small scale and large-scale preparation methods, (4) in vitro and in vivo studies.

Conclusion

We identified two studies describing the procedures which are simple, reproducible, economical, provide a good yield of platelets, and therefore can be considered methods for further tissue-specific and pathology-specific standardizations of PRP and its derivatives. We recommend further randomized studies to understand the full therapeutic potential of the constituents of PRP and its derivatives.

Nucleofection of Adipose Mesenchymal Stem/Stromal Cells: Improved Transfection Efficiency for GMP Grade Applications

Nucleofection (NF) is a safe, non-viral transfection method, compatible with Good Manufacturing Practice guidelines. Such a technique is useful to improve therapeutic effectiveness of adipose tissue mesenchymal stem cells (ASC) in clinical settings, but improvement of NF efficiency is mandatory. Supernatant rich in growth factors (SRGF) is a clinical-grade medium additive for ASC expansion. We showed a dramatically increased NF efficiency and post-transfection viability in ASC expanded in presence of SRGF (vs. fetal bovine serum). SRGF expanded ASC were characterized by increased vesicle endocytosis but lower phagocytosis properties. SRGF increased n-6/n-3 ratio, reduced membrane lipid raft occurrence, and lowered intracellular actin content in ASC. A statistical correlation between NF efficiency and lipid raft availability on cell membranes was shown, even though a direct relationship could not be demonstrated: attempts to selectively modulate lipid rafts levels were, in fact, limited by technical constraints. In conclusion, we reported for the first time that tuning clinical-grade compatible cell culture conditions can significantly improve ASC transfection efficiency by a non-viral and safe approach. A deep mechanistic characterization is extremely complex, but we can hypothesize that integrated changes in membrane structure and intracellular actin content could contribute to explain SRGF impact on ASC NF efficiency.

In Ovarian Cancer Multicellular Spheroids, Platelet Releasate Promotes Growth, Expansion of ALDH+ and CD133+ Cancer Stem Cells, and Protection against the Cytotoxic Effects of Cisplatin, Carboplatin and Paclitaxel

A high platelet count is associated with a poor prognosis in ovarian cancer (OvCa). Despite good clinical responses with platinating agents in combination with taxanes, numerous OvCa patients relapse due to chemotherapy resistance. Here, we report that treatment of OvCa cells A2780, OVCAR5 and MDAH with releasate from activated platelets (PR) promoted multicellular tumor spheroid (MCTS) formation. These OvCa-MCTSs had increased percentages of CD133+ and aldehyde dehydrogenase (ALDH)+ cells, bona fide markers of OvCa cancer stem cells (CSCs). PR increased OVCAR5- and MDAH-MCTS viability and decreased the cytotoxic and pro-apoptotic effects of paclitaxel, cisplatin and carboplatin. PR increased the volume of spontaneously formed OVCAR8-MCTSs and counteracted their size reduction due to cisplatin, carboplatin and paclitaxel treatment. PR promoted the survival of ALDH+ and CD133+ OvCa cells during cisplatin, carboplatin and paclitaxel treatment. In conclusion, molecules and growth factors released by activated platelets (EGF, PDGF, TGF-β, IGF and CCL5) may protect tumor cells from chemotherapy by promoting the expansion of ALDH+ and CD133+ OvCa-CSCs, favoring drug resistance and tumor relapse.

Optimized platelet rich plasma releasate (O-rPRP) repairs galactosemia-induced ovarian follicular loss in rats by activating mTOR signaling and inhibiting apoptosis

Platelet rich plasma contains a collection of growth factors, and an optimal formulation, named O-rPRP, contains the highest possible concentration of growth factors.

Purpose

Challenging the healing power of O-rPRP in a high-galactose diet-induced premature ovarian insufficiency (POI) experimental rat model.

Methods

Rats were divided into four groups of ten rats each and treated for four week as follows; 1) the control group, fed with normal diet and received intraperitoneal (i.p.) injection of PBS once/week; 2) the POI group, fed with galactose diet (50%) and received PBS (i.p.) once/week; 3) the POI/O-rPRP group, fed a 50% galactose diet and received O-rPRP (i.p.) once/week; 4) the O-rPRP group (negative control), fed with a normal diet and received O-rPRP (i.p.) once/week. The levels of galactose, follicle stimulating hormone, 17 β-estradiol, anti-mullerian hormone and inhibin B were measured in serum samples. Western blotting and quantitative real-time PCR assays were employed to investigate the levels of miR-223, β1 integrin, p70S6k and MCL-1 in ovarian tissues.

Results

After O-rPRP treatment, β1 integrin expression was enhanced, and miR-223 expression was decreased. Unlike the untreated galactose group, in the group treated with O-rPRP, p70S6k and MCL-1 expression levels were increased, indicating that the mTOR growth signaling pathway was active and that apoptosis was inactive. After the introduction of O-rPRP, the number of follicles and the follicular maturation improved, which was consistent with the improvement of inhibin B levels and subsequent inhibition of FSH.

Conclusion

O-rPRP inhibited galactose-induced excessive atresia and provided an overall protective effect on the ovarian follicles.

Platelet-derived bio-products: Classification update, applications, concerns and new perspectives

Platelet derived bio-products in the form of platelet rich plasma, plasma rich in growth factors, or plasma-free platelet releasates, are being studied worldwide with the aim of proving their efficacy in tissue regeneration within many different clinical areas, such as traumatology, maxillofacial surgery, ophthalmology, dermatology and otorhinolaryngology, amongst others. The current lack of consensus in the preparation method and application form, or in the quality assessment of each bio-product, precludes adequate interpretation of the relevance of reported clinical outcomes, and, while many in clinicians are very positive about them, many are sceptic. Relevant aspects of these products are considered to propose a classification nomenclature which would aid a comprehensive comparison of clinical outcomes of bio-products of the same characteristics. Finally, the uses of platelet-derived bio-products in in vitro culture (for cell therapy purposes) as a substitute of animal-origin sera, and other future perspectives of applications of platelet-derived bio-products are discussed.

Topical effect of allogenous serum rich in growth factors (SRGF) on diabetic skin wound in rat

Diabetic foot ulcer is a major complication of diabetes mellitus with negative effects on the life quality. Management of diabetic foot ulcers is a big challenge with poor and low sufficient outcome management. Therefore, achievement to effective treatments may treat these ulcers. Nowdays, platelet products are used as an effective and safe agent for promotion of healing proposes in regenerative medicine. Serum rich in growth factors (SRGF) is a source of released growth factors from the platelets. In the present study, effect of allogenous SRGF was investigated on the streptozotocin (STZ)-induced diabetic wounds in rats. STZ (50 mg/kh, SC) caused significant increase in blood glucose and weight loss in rats. Full thickness cutaneous wounds (8 mm diameter) were created bilaterally on the dorsal of the diabetic rats. SRGF was injected at the edges of the wounds of one side only on the first day, and the contrary sides were considered as the control group. The percentage of wound contraction was demonstrared on day 3, 7, 11 after surgery. Tissue specimens were collected for microscopic study on days 7 and 14. Results showed a significant higher rate of wound contraction on days 5 and 7 in the treated group. Histopathologic findings displayed acceleration of re-epithelialization, increased angiogenesis and dense collagen fibers with better organization in the treated group. Current study suggests that SRGF was efficient because facilate wound healing and showed rapid re-epithelialization and increased angiogenesis.

The use of fat grafting and platelet-rich plasma for wound healing: A review of the current evidence

Fat grafting is becoming a common procedure in regenerative medicine because of its high content of growth factors and adipose derived stem cells (ADSCs) and the ease of harvest, safety, and low cost. The high concentration of ADSCs found in fat has the potential to differentiate into a wide range of wound-healing cells including fibroblasts and keratinocytes as well as demonstrating proangiogenic qualities. This suggests that fat could play an important role in wound healing. However retention rates of fat grafts are highly variable due in part to inconsistent vascularisation of the transplanted fat. Furthermore, conditions such as diabetes, which have a high prevalence of chronic wounds, reduce the potency and regenerative potential of ADSCs. Platelet-rich plasma (PRP) is an autologous blood product rich in growth factors, cell adhesion molecules, and cytokines. It has been hypothesised that PRP may have a positive effect on the survival and retention of fat grafts because of improved proliferation and differentiations of ADSCs, reduced inflammation, and improved vascularisation. There is also increasing interest in a possible synergistic effect that PRP may have on the healing potential of fat, although the evidence for this is very limited. In this review, we evaluate the evidence in both in vitro and animal studies on the mechanistic relationship between fat and PRP and how this translates to a benefit in wound healing. We also discuss future directions for both research and clinical practice on how to enhance the regenerative potential of the combination of PRP and fat.

1H-NMR and MALDI-TOF MS as metabolomic quality control tests to classify platelet derived medium additives for GMP compliant cell expansion procedures

Introduction

Ex vivo cell expansion under Good Manufacturing Practice (GMP) guidelines can be performed using medium additives containing human growth factors from platelets. These products can differently affect proliferation of adipose mesenchymal stromal stem cells (ASC). Qualification of medium additive performance is required for validation under GMP regulations: assessment of growth factor concentrations is not sufficient to predict the biological activity of the product batch. Proton nuclear magnetic resonance spectrometry (¹H-NMR) and matrix-assisted laser desorption/ionization time of flight mass spectroscopy (MALDI-TOF MS) provide wide molecular characterization of samples.

Aims

We aimed to assess if ¹H-NMR and MALDI-TOF MS techniques can be used as quality control test potentially predicting the impact of a medium additive on cell proliferation.

Methods

We tested the impact on ASC growth rate (cell proliferation assessment and cell morphology analysis) of four medium additives, obtained by different methods from human platelet apheresis product. In order to classify each medium additive, we evaluated growth factor concentrations and spectra obtained by ¹H-NMR and by MALDI-TOF MS.

Results

Medium additive obtained by CaCl₂ activation of platelet rich products induced higher proliferation rate vs additive derived from platelet depleted ones. Additives obtained by freeze-and-thaw methods weakly induced ASC proliferation. As expected, principal component analysis of growth factor concentrations did not unravel specific biochemical features characterizing medium additives in relation with their biological activity. Otherwise, while ¹H-NMR showed a partial resolution capacity, analysis of MALDI-TOF MS spectra allowed unambiguous distinction between the medium additives we used to differently stimulate cell growth in vitro.

Discussion

MALDI-TOF and, despite limitations, ¹H-NMR are promising cost effective and reliable quality controls to classify the potential of a medium additive to promote ASC growth. This can represent, after further investigations and appropriate validation, a significant advantage for GMP compliant manufacturing of advanced cell therapy products.

Intra-articular effects of combined xenogenous serum rich in growth factors (SRGF) and vitamin C on histopathology grading and staging of osteoarthritis in rat model

OBJECTIVE

Osteoarthritis (OA) is one of the most common degenerative diseases especially in the knee joint. The definitive method for the treatment of this disease is not known. In recent years, use of platelet-derived products has been considered as a new therapeutic approach because of its low cost, easy to use, and minimum side effects. Serum rich of growth factors (SRGF) is one of the biological compounds used to healing and regeneration. Its effects may improve in combination with antioxidants such as vitamin C. This vitamin increases the synthesis of proteoglycans by chondrocytes. The present study investigated effect of xenogenous SRGF in combination with vitamin C on the monosodium iodoacetate-induction osteoarthritis in rats.

METHODS

Animals were randomly categorized into three groups including OA, SRGF, and vitamin C+SRGF. Treatments were performed with 3 time intra-articular injection in weekly intervals. Knee samples were taken after two weeks of the last treatment for histopathologic investigations.

RESULTS

In the OA group, surface fibrillation and irregularity, multiple clefts, loss of chondrocytes, proteoglycan depletion with Toluidine blue staining were detected. In the treated group with SRGF/vitamin C, the severity of degenerative lesions was decreased. Chondrocytes had proliferated and matrix proteoglycan increased in compared to the SRGF and OA groups. Also, osteoarthritis stage was markedly reduced in this group rather than two other groups.

CONCLUSION

The results of this study show the synergic effect of vitamin C and growth factors on accelerating articular repair.

Improved GMP compliant approach to manipulate lipoaspirates, to cryopreserve stromal vascular fraction, and to expand adipose stem cells in xeno-free media

Background

The stromal vascular fraction (SVF) derived from adipose tissue contains adipose-derived stromal/stem cells (ASC) and can be used for regenerative applications. Thus, a validated protocol for SVF isolation, freezing, and thawing is required to manage product administration. To comply with Good Manufacturing Practice (GMP), fetal bovine serum (FBS), used to expand ASC in vitro, could be replaced by growth factors from platelet concentrates.

Methods

Throughout each protocol, GMP-compliant reagents and devices were used. SVF cells were isolated from lipoaspirates by a standardized enzymatic protocol. Cells were cryopreserved in solutions containing different albumin or serum and dimethylsulfoxide (DMSO) concentrations. Before and after cryopreservation, we analyzed: cell viability (by Trypan blue); immunophenotype (by flow cytometry); colony-forming unit-fibroblast (CFU-F) formation; and differentiation potential. ASC, seeded at different densities, were expanded in presence of 10% FBS or 5% supernatant rich in growth factors (SRGF) from platelets. The differentiation potential and cell transformation grade were tested in expanded ASC.

Results

We demonstrated that SVF can be obtained with a consistent yield (about 185 × 10³ cells/ml lipoaspirate) and viability (about 82%). Lipoaspirate manipulation after overnight storage at +4 °C reduced cell viability (−11.6%). The relative abundance of ASC (CD34⁺CD45⁻CD31^–) and endothelial precursors (CD34⁺CD45⁻CD31⁺) in the SVF product was about 59% and 42%, respectively. A period of 2 months cryostorage in autologous serum with added DMSO minimally affected post-thaw SVF cell viability as well as clonogenic and differentiation potentials. Viability was negatively affected when SVF was frozen at a cell concentration below 1.3 × 10⁶ cells/ml. Cell viability was not significantly affected after a freezing period of 1 year.

Independent of seeding density, ASC cultured in 5% SRGF exhibited higher growth rates when compared with 10% FBS. ASC expanded in both media showed unaltered identity (by flow cytometry) and were exempt from genetic lesions. Both 5% SRGF- and 10% FBS-expanded ASC efficiently differentiated to adipocytes, osteocytes, and chondrocytes.

Conclusions

This paper reports a GMP-compliant approach for freezing SVF cells isolated from adipose tissue by a standardized protocol. Moreover, an ASC expansion method in controlled culture conditions and without involvement of animal-derived additives was reported.

Standardization of platelet releasate products for clinical applications in cell therapy: a mathematical approach

BACKGROUND

Standardized animal-free components are required for manufacturing cell-based medicinal products. Human platelet concentrates are sources of growth factors for cell expansion but such products are characterized by undesired variability. Pooling together single-donor products improves consistency, but the minimal pool sample size was never determined.

METHODS

Supernatant rich in growth factors (SRGF) derived from n = 44 single-donor platelet-apheresis was obtained by CaCl₂ addition. n = 10 growth factor concentrations were measured. The data matrix was analyzed by a novel statistical algorithm programmed to create 500 groups of random data from single-donor SRGF and to repeat this task increasing group statistical sample size from n = 2 to n = 20. Thereafter, in created groups (n = 9500), the software calculated means for each growth factor and, matching groups with the same sample size, the software retrieved the percent coefficient of variation (CV) between calculated means. A 20% CV was defined as threshold. For validation, we assessed the CV of concentrations measured in n = 10 pools manufactured according to algorithm results. Finally, we compared growth rate and differentiation potential of adipose-derived stromal/stem cells (ASC) expanded by separate SRGF pools.

RESULTS

Growth factor concentrations in single-donor SRGF were characterized by high variability (mean (pg/ml)-CV); VEGF: 950-81.4; FGF-b: 27-74.6; PDGF-AA: 7883-28.8; PDGF-AB: 107834-32.5; PDGF-BB: 11142-48.4; Endostatin: 305034-16.2; Angiostatin: 197284-32.9; TGF-β1: 68382-53.7; IGF-I: 70876-38.3; EGF: 2411-30.2). In silico performed analysis suggested that pooling n = 16 single-donor SRGF reduced CV below 20%. Concentrations measured in 10 pools of n = 16 single SRGF were not different from mean values measured in single SRGF, but the CV was reduced to or below the threshold. Separate SRGF pools failed to differently affect ASC growth rate (slope pool A = 0.6; R² = 0.99; slope pool B = 0.7; R² 0.99) or differentiation potential.

DISCUSSION

Results deriving from our algorithm and from validation utilizing real SRGF pools demonstrated that pooling n = 16 single-donor SRGF products can ameliorate variability of final growth factor concentrations. Different pools of n = 16 single donor SRGF displayed consitent capability to modulate growth and differentiation potential of expanded ASC. Increasing the pool size should not further improve product composition.

The effect of intraarticular serum rich in growth factors (SRGF) on knee osteoarthritis in the rat model

Osteoarthritis (OA) is a degenerative joint disease with high incidence in world. Various treatments have been used for decreasing pain and improving physical function without clearly beneficial evidences. Nowadays, platelet-rich therapy is used as a novel approach in field of regenerative medicine. The present study evaluated the effect of intraarticular serum rich in growth factors (SRGF) on the monosodium iodoacetate induced-osteoarthritis in rat model. SRGF was injected 3 times weekly. Femorotibial joints were examined 2 weeks after last injection. Histopathologic results showed remarkable articular regeneration in the SRGF treated rats. Our findings were less surface irregularities and articular clefts, proliferation of chondrocytes and increasing synthesis of matrix proteoglycan with toluidine blue staining. Destroyed articular cartilage was repaired by fibro-hyaline cartilage in contrast to the OA rats that filled with fibrovascular tissues. The microscopic score had decreased in the treatment group. We concluded that SRGF, as a source of growth factors, have chondroinductive capacity with regard to enhancement of cartilage regeneration.