The effect of four different freezing conditions and time in frozen storage on the concentration of commonly measured growth factors and enzymes in equine platelet-rich plasma over six months

Platelet-Rich Plasma-Embedded Porous Polycaprolactone Film with a Large Surface Area for Effective Hemostasis

BACKGROUND

Uncontrollable and widespread bleeding caused by surgery or sudden accidents can lead to death if not treated with appropriate hemostasis. To prevent excessive life-threatening bleeding, various hemostatic agents based on polymeric biomaterials with various additives for accelerated blood coagulation have been adopted in clinical fields. In particular, platelet-rich plasma (PRP), which contains many blood coagulation factors that can accelerate blood clot formation, is considered as one of the most effective hemostatic additives.

METHODS

We investigated a PRP-embedded porous film using discarded (expired) PRP and a film with a leaf-stacked structure (FLSS), as a hemostatic agent to induce rapid hemostasis. The film, which contained an LSS on one side (PCL-FLSS), was fabricated by a simple heating-cooling technique using tetraglycol and polycaprolactone (PCL) film. Activated PRP was obtained by the thawing of frozen PRP at the end of its expiration date (the platelet cell membrane is disrupted during the freezing and thawing of PRP, thus releasing various coagulation factors) and embedded in the PCL-FLSS (PRP-FLSS).

RESULTS

From in vitro and in vivo experiments using a rat hepatic bleeding model, it was recognized that PRP-FLSS is not only biocompatible but also significantly accelerates blood clotting and thus prevents rapid bleeding, probably due to a synergistic effect of the sufficient supply of various blood coagulants from activated PRP embedded in the LSS layer and the large surface area of the LSS itself.

CONCLUSION

The study suggests that PRP-FLSS, a combination of a porous polymer matrix with a unique morphology and discarded biofunctional resources, can be an advanced hemostatic agent as well as an upcycling platform to avoid the waste of biofunctional resources.

Freeze-drying protocols and methods of maintaining the in-vitro biological activity of horse platelet lysate

Platelet lysate, derived from platelets, are valuable biological products rich in bioactive molecules. Their use promotes tissue healing and modulates inflammation. However, maintaining the stability and bioactivity of platelet lysate is challenging since they degrade rapidly at room temperature. This study focused on the possibility to confer enhanced stability to freeze-dried equine platelet lysate as an alternative to platelet-rich plasma (PRP). Platelet lysate (PL) was derived from PRP and freeze-dried either as such or using various adjuvants. Primary cell cultures of porcine Vascular Wall-Mesenchymal Stem Cells were treated with different PL formulations, and cell viability was assessed using an MTT assay. Overall, the addition of PL significantly improved cell viability as compared to controls without growth factor supplementation or with foetal bovine serum. Notably, the freeze-drying process maintained the effectiveness of the PL for at least a week. Furthermore, the study revealed that varying the horse as the source of PL could yield varying effects on cell viability. Detailed freeze-drying protocols were established, including freezing, primary drying and secondary drying phases, and the type of adjuvant. This study demonstrated the potential of freeze-dried equine PL as a viable alternative to PRP and highlighted the importance of precise freeze-drying protocols and adjuvants for standardization. Equine PL showed promise for medical treatment in horses, offering advantages such as extended shelf life, ease of handling, and reduced transportation costs, with the potential for broadened therapeutic usage.

Enhanced wound regeneration by PGS/PLA fiber dressing containing platelet-rich plasma: an in vitro study

Novel wound dressings with therapeutic effects are being continually designed to improve the wound healing process. In this study, the structural, chemical, physical, and biological properties of an electrospun poly glycerol sebacate/poly lactide acid/platelet-rich plasma (PGS/PLA-PRP) nanofibers were evaluated to determine its impacts on in vitro wound healing. Results revealed desirable cell viability in the Fibroblast (L929) and macrophage (RAW-264.7) cell lines as well as human umbilical vein endothelial cells (HUVEC). Cell migration was evident in the scratch assay (L929 cell line) so that it promoted scratch contraction to accelerate in vitro wound healing. Moreover, addition of PRP to the fiber structure led to enhanced collagen deposition (~ 2 times) in comparison with PGS/PLA scaffolds. While by addition PRP to PGS/PLA fibers not only decreased the expression levels of pro-inflammatory cytokines (IL-6 and TNF-α) in RAW-264.7 cells but also led to significantly increased levels of cytokine (IL-10) and the growth factor (TGF-β), which are related to the anti-inflammatory phase (M2 phenotype). Finally, PGS/PLA-PRP was found to induce a significant level of angiogenesis by forming branching points, loops, and tubes. Based on the results obtained, the PGS/PLA-PRP dressing developed might be a promising evolution in skin tissue engineering ensuring improved wound healing and tissue regeneration.

Ultrafast gelling bioadhesive based on blood plasma and gelatin for wound closure and healing

Tissue adhesives offer a plethora of advantages in achieving efficient wound closure over conventional sutures and staples. Such materials are of great value, especially in cases where suturing could potentially damage tissues or compromise blood flow or in cases of hard-to-reach areas. Besides providing wound closure, the tissue adhesives must also facilitate wound healing. Previously, plasma-based tissue adhesives and similar bioinspired strategies have been utilized to aid in wound healing. Still, their application is constrained by factors such as high cost, diminished biocompatibility, prolonged gelation times, inadequate swelling, quick resorption, as well as short-term and inconsistent efficacy. To address these limitations, we report the development of a highly biocompatible and ultrafast-gelling tissue adhesive hydrogels. Freeze-dried platelet-rich plasma, heat-denatured freeze-dried platelet-poor plasma, and gelatin were utilized as the base matrix. Gelation was initiated by adding tetrakis hydroxymethyl phosphonium chloride. The fabricated gels displayed rapid gelation (3-4 s), low swelling, increased proliferation, and migration against L929 cells and had porcine skin tissue adhesion strength similar to that of plasma-based commercial glue (Tisseel®).

Enhancing Fertility: A Case Report of the Frozen Platelet-Rich Plasma Therapy for Thin Endometrium and Poor Ovarian Reserve

A 33-year-old female patient was assessed for primary infertility due to thin endometrium and poor ovarian reserve (POR). The effectiveness of platelet-rich plasma (PRP) therapy was evaluated in terms of thickening the endometrium and enhancing implantation. The patient also had a history of four intrauterine inseminations and one intracytoplasmic sperm injection (ICSI), along with low anti-Müllerian hormone (AMH) and high follicle-stimulating hormone levels which showed POR. Gonadotropins are given to enhance follicular growth, while agonists and antagonists are given to prevent premature luteinizing hormone surge and suppress the top axis. During the first oocyte pick-up (OPU), five oocytes were retrieved. ICSI was done to make fertilization easier. On day 5, the embryos had degraded from their initial high quality. The patient was advised to undergo treatment with PRP. The endometrial thickness was significantly thicker, raising the chance of implantation. The second OPU was scheduled, resulting in the retrieval of 14 oocytes on the same day ICSI was performed. High-quality blastocysts (4AA) were produced and transferred during embryo transfer, and the patient tolerated the procedure well. The clinical success of the pregnancy outcome was confirmed by another beta-human chorionic gonadotropin test.

The Effect of a Rotating Magnetic Field on the Regenerative Potential of Platelets

Platelets are actively involved in tissue injury site regeneration by producing a wide spectrum of platelet-derived growth factors such as PDGF (platelet-derived growth factor), IGF-1 (insulin-like growth factor), TGF-β1 (transforming growth factor β), FGF (fibroblast growth factor), etc. A rotating magnetic field (RMF) can regulate biological functions, including reduction or induction regarding inflammatory processes, cell differentiation, and gene expression, to determine the effect of an RMF on the regenerative potential of platelets. The study group consisted of 30 healthy female and male volunteers (n = 15), from which plasma was collected. A portion of the plasma was extracted and treated as an internal control group. Subsequent doses of plasma were exposed to RMF at different frequencies (25 and 50 Hz) for 1 and 3 h. Then, the concentrations of growth factors (IGF-1, PDGF-BB, TGF-β1, and FGF-1) were determined in the obtained material by the ELISA method. There were statistically significant differences in the PDGF-BB, TGF-β1, IGF-1, and FGF-1 concentrations between the analyzed groups. The highest concentration of PDGF-BB was observed in the samples placed in RMF for 1 h at 25 Hz. For TGF-β1, the highest concentrations were obtained in the samples exposed to RMF for 3 h at 25 Hz and 1 h at 50 Hz. The highest concentrations of IGF-1 and FGF-1 were shown in plasma placed in RMF for 3 h at 25 Hz. An RMF may increase the regenerative potential of platelets. It was noted that female platelets may respond more strongly to RMF than male platelets.

Combination Therapy with Platelet-Rich Plasma and Epidermal Neural Crest Stem Cells Increases Treatment Efficacy in Vascular Dementia

This study aimed to evaluate the efficacy and treatment mechanism of platelet-rich plasma (PRP) and neural crest-derived epidermal stem cells (ESCs) in their administration alone and combination in vascular dementia (VaD) model by two-vessel occlusion (2VO). Methods. Sixty-six rats were divided into six groups: the control, sham, 2VO + vehicle, 2VO + PRP, 2VO + ESC, and 2VO + ESC + PRP. The treated groups received 1 million cells on days 4, 14, and 21 with or without 500 µl PRP (twice a week) after 2VO. The memory performance and anxiety were evaluated by behavioral tests including open field, passive avoidance, and Morris water maze. The basal-synaptic transmission (BST) and long-term potentiation (LTP) were assessed through field-potential recordings of the CA1. The mRNA expression levels of IGF-1, TGF-β1, PSD-95, and GSk-3β were measured in the rat hippocampus by quantitative reverse transcription polymerase chain reaction. Results. The results demonstrated impaired learning, memory, and synaptic plasticity in the 2VO rats, along with a significant decrease in the expression of IGF-1, TGF-β1, PSD-95, and upregulation of GSK-3β. Treatment with ESC alone and ESC + PRP showed similar improvements in spatial memory and LTP induction, with associated upregulation of PSD-95 and downregulation of GSK-3β. However, only the ESC + PRP group showed recovery in BST. Furthermore, combination therapy was more effective than PRP monotherapy for LTP and memory. Conclusions. The transplantation of ESC showed better effects than PRP alone, and combination therapy increased the treatment efficacy with the recovery of BST. This finding may be a clue for the combination therapy of ESC and PRP for VaD.

Equine Platelet-Rich Plasma

Platelet-rich plasma (PRP) is an orthobiologic therapy composed of platelets, leukocytes, red blood cells, and plasma proteins. PRP has been used for 20 years, but progress determining efficacy has been slow. The definitions and classification of PRP are reviewed, and the use of PRP for tendon, ligament, and joint disease is discussed with a focus on findings of basic science and clinical studies, platelet activation, concurrent administration of nonsteroidal anti-inflammatory drugs, and treatment complications. Finally, the advantages of platelet lysates and freeze-dried platelets are discussed. The promising results of a PRP lysate optimized for antibiofilm and antimicrobial properties are introduced.

Serum Insulin-like Growth Factor-1 Is a Biomarker of Testosterone Production and Intact Acrosome in Asian Elephants (Elephas maximus)

Simple Summary

In Thailand, the low fertility rate of Asian elephants has been identified. Factors contributing to poor semen quality in the elephants are not fully understood. Insulin-like growth factor-1 (IGF-1) is related to male infertility. It plays an essential role in testicular development by stimulating cell proliferation, differentiation, and steroidogenesis. In addition, there is increasing evidence that IGF-1 plays a critical role in spermatogenesis. This may be conducive to finding the causes of poor sperm quality in Asian elephants (Elephas maximus). In the present study, we investigated the relationships among serum IGF-1, serum testosterone level, and semen parameters in seven elephant bulls. The findings suggest that serum IGF-1 concentration is likely to predict sperm quality like acrosome integrity. The further mechanism by which IGF-1 affects sperm quality requires further investigation.

Abstract

The objective of this study was to find relationships among serum IGF-1, serum testosterone, seminal plasma IGF-1 concentrations and semen parameters in Asian elephants (Elephas maximus). A total of 17 ejaculates (one to three ejaculates/bull) were collected from seven captive elephant bulls by performing rectal massage. Before each ejaculation, blood samples were obtained for serum IGF-1 and testosterone assays. Subsequently, the semen characteristics of each ejaculate were evaluated. Mean serum IGF-1 concentration of elephant bulls was estimated as 326.3 ± 114.6 ng/mL (median, 286.2 ng/mL; range, 167.4–542.7 ng/mL). An increase in serum IGF-1 concentration was found to correlate with the percentage of spermatozoa with intact acrosomes. In addition, IGF-1 concentration was positively correlated with testosterone level. However, seminal IGF-1 concentrations could not be detected. In conclusion, our findings suggest that serum IGF-1 concentration is likely a biomarker of normal testicular functions, particularly spermatogenesis in elephants. Moreover, this commercial IGF-1 ELISA is eligible for analyzing serum IGF-1 concentration in Asian elephants.

Pulsed Electric Fields for Valorization of Platelets with No Therapeutic Value towards a High Biomedical Potential Product—A Proof of Concept

Nowadays, the standard media used in clinical-scale mesenchymal stem cell (MSC) production to supply hundreds of clinical trials uses animal-derived components as supplements, which raises several health concerns. Consequently, the development of xeno-free media supplements has emerged. In the current study, the effect of pulse electric field (PEF) application to platelet concentrates (PC) with no therapeutic value for producing platelet releasates (PR) able to sustain the ability of bone marrow-MSCs (BM-MSCs) to self-renew and differentiate was tested. It was demonstrated that PEF application to PC induces platelet activation and growth factor (GF) release, namely PDGF, FGF, IGF, and TGF-β. The highest GF release was observed for TGF-β, achieving similar levels to those attained in platelet lysates (PL). BM-MSCs expanded in the presence of PR obtained by the application of PEF (7 pulses of 10 and 12.5 kV/cm) to PC (PR PEF) retained the characteristic MSC cell-surface markers, and the ability to proliferate and differentiate into osteogenic, adipogenic, and chondrogenic lineages. In this study, evidence is provided that PR PEF represents a suitable alternative to fetal bovine serum (FBS) for use in MSC production.

Platelet-Rich Plasma as an Orthobiologic: Clinically Relevant Considerations

Platelet-rich plasma (PRP) is an autologous blood-derived product processed to concentrate platelets and the associated growth factors. PRP has been shown to be relatively well-tolerated and safe to use for a number of conditions in humans, equines, and canines. There are multiple commercial systems that have been validated for canine use. These systems use a variety of methodologies to produce a PRP product. However, PRP products have been shown to differ greatly between systems. Further study is needed to fully elucidate optimal component concentrations for various indications.

Evaluation of Platelet and Leukocyte Counts in Canine Platelet-Rich Plasma Obtained After Successive Blood Collections From the Same Patient and the Effects of Freezing on the Concentration of Growth Factors Present in It

Objective

The purpose of this study was 2-fold: to evaluate whether the timing of collection influences the platelet counts and leukocyte counts of PRP samples, and to evaluate growth factor concentrations in canine PRP after freezing and storage without a preservation agent for 6 months of time.

Materials and Methods

Whole blood collection was performed three times over the course of 4 weeks. All PRP samples were evaluated with a CBC analysis. The PRP samples were frozen and stored without a preservation agent for the duration of the 4-week study.

Results

The platelet and leukocyte counts were not statistically significant between the timing of blood draws over the course of 4 weeks. All three growth factors were present in measurable quantities after freezing and storage for 6 months without a preservation agent.

Clinical Relevance

PDGF, TGF-β1, and VEGF were all present in measurable quantities. Furthermore, PDGF and TGF-β1 were correlated with platelet count of the final PRP. VEGF concentrations were able to be quantified. We correctly hypothesized growth factor concentrations would be present and measurable in canine PRP frozen and stored without a preservation agent for 6 months.

The protective effect of co-administration of platelet-rich plasma (PRP) and pentoxifylline (PTX) on cyclophosphamide-induced premature ovarian failure in mature and immature rats

Cyclophosphamide (CP), as an antineoplastic agent, causes premature ovarian failure (POF) due to ovarian toxicity and subsequent infertility in women. Platelet-rich plasma (PRP) has accumulated significant attention in regenerative medicine. Pentoxifylline (PTX) as a methylxanthine derivative has been shown to have antioxidant and antiapoptotic properties. The aim of this study was to evaluate the protective effect of PRP and PTX on CP-induced POF. Fifty mature and immature female rats were assigned into five groups: control, CP (75 mg/kg, intraperitoneal [ip] on days 1 and 10 to induce POF), CP + PRP (200 μl, ip, half an hour after CP injection on day 1 and 10), CP + PTX (50 mg/kg, orally, half an hour after CP injection daily for 21 day), and CP + PRP + PTX. At the end of experiments on day 21, measurement of body weight, ovarian parameters (ovarian volume, follicular granulosa cell layers diameter, oocyte diameter, and the number of granulosa cells), measurement of ovarian hormone in sera for estradiol (E₂), and anti-Mullerian hormone (AMH), as well as biochemical assessment were performed.The results showed that CP significantly reduced the ovarian parameters, E₂, AMH, superoxide dismutase (SOD) activity and increased Malondialdehyde (MDA) levels compared to the control group (p < 0.001). Our results also indicated that all histomorphometric parameters and biochemical markers in CP-induced POF, were preserved close to normal by PRP and PTX treatments in both mature and immature rats (p < 0.001). Therefore, it is concluded that the co-administration of PRP and PTX can protect the ovary from CP-induced POF.

An Evaluation of the Effect of Activation Methods on the Release of Growth Factors from Platelet-Rich Plasma

BACKGROUND

Activation of platelets in platelet-rich plasma may improve growth factor release, thus enhancing regenerative properties. The authors investigated whether different methods of platelet-rich plasma activation affected growth factor release kinetics over time.

METHODS

Platelet-rich plasma from 20 healthy volunteers was processed by six different methods: (1) control (nonactivated); (2) activation with calcium chloride; (3) activation with calcium chloride and ethanol; (4) activation with calcium chloride and ethanol at 4°C; (5) activation with calcium chloride and ethanol with vitamin C; (6) activation with calcium chloride and ethanol with vitamin C at 4°C. Concentration of secreted vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and insulin-like growth factor over 24 hours was measured by immunoassay.

RESULTS

Calcium chloride-activated platelet-rich plasma produced significantly more insulin-like growth factor at 1 hour compared to cold and vitamin C platelet-rich plasma, and calcium chloride plus ethanol produced significantly more at 24 hours compared to vitamin C platelet-rich plasma. The addition of vitamin C reduced release of PDGF over time. Activation with calcium chloride and ethanol with or without cold temperature produced a gradual PDGF release as opposed to calcium chloride alone, which caused higher PDGF within 4 hours. There were no significant differences between groups for VEGF, although calcium chloride and cooled platelet-rich plasma approached significance for producing more than vitamin C platelet-rich plasma.

CONCLUSIONS

Activation of platelet-rich plasma does not significantly improve growth factor secretion, which is made worse by the addition of vitamin C, a platelet inhibitor. Ethanol does not negatively impact growth factor production and may offer a more gradual release.

CLINICAL RELEVANCE STATEMENT

These findings will help guide platelet-rich plasma preparation methods where therapeutic growth factors are used.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Effects of platelet-rich plasma on the memory impairment, apoptosis, and hippocampal synaptic plasticity in a rat model of hepatic encephalopathy

OBJECTIVES

In the present study, we aimed to determine whether intraperitoneal injection of platelet-rich plasma (PRP) could have a neuroprotective effect on learning, memory, and synaptic plasticity impairment as well as hippocampal apoptosis in rats with hepatic encephalopathy induced by bile duct ligated (BDL).

METHODS

The rats were divided into four groups: the control, sham, BDL+ V (vehicle), and BDL+ PRP. The BDL rats were treated with PRP immediately after the surgery, and the injection was done every 3 days for 30 days. The passive avoidance and Morris water maze tests were used for the evaluation of learning and memory. The long-term potentiation (LTP), basal-synaptic transmission, and paired-pulse ratio, as an index for measurement of neurotransmitter release probability, were evaluated by field-potential recording. After taking a blood sample for assessment of the liver enzymes, the animals were sacrificed and their hippocampus was removed for evaluation of cleaved caspase-3 by Western blot.

RESULTS

Serological assessment of the liver function showed that BDL severely impaired the liver function. Also, PRP treatment could partially improve the liver dysfunction along with recovery in fear memory and spatial learning memory performance, LTP, basal-synaptic transmission, and neurotransmitter release probability. PRP-treated rats also showed a significant reduction in neuronal apoptosis in the CA1 area.

CONCLUSIONS

The results of this study suggest that PRP improves cognitive performance and synaptic plasticity in BDL rats via direct neuroprotective property and/or indirectly by improvement of hepatic dysfunction.

The Effect of a Single Freeze-Thaw Cycle on Matrix Metalloproteinases in Different Human Platelet-Rich Plasma Formulations

Storing platelet-rich plasma (PRP) for future use is a compelling approach, presuming the retention of biological properties is maintained. However, certain factors in PRP preparations have deleterious effects for the treatment of certain musculoskeletal conditions. The purpose of this study was to measure and compare matrix metalloproteinase protein (MMP) concentrations between fresh and freeze-thawed leukocyte-rich PRP (LR-PRP) inactivated (LR-I) and activated (LR-A) preparations, and leukocyte-poor PRP (LP-PRP) inactivated (LP-I) and activated (LP-A) preparations. A volume of 60 mL of whole blood was drawn from 19 healthy donors. LP-I and LR-I samples were processed using a manual extraction and centrifugation methodology. LP-A and LR-A products were activated with 10% CaCl2 and recombinant thrombin. Blood fractions were either immediately assayed and analyzed or stored at -80 °C for 24, 72 and 160 h. Multiplex immunoassay was used to measure MMP-1, MMP-2, MMP-3, MMP-9, MMP-10, and MMP-12. MMP-1 concentrations increased in LR-A (p < 0.05) and MMP-9 significantly increased in LR-I (p < 0.05), while MMP-2 significantly decreased in LR-I (p < 0.05) and MMP-3 concentrations significantly decreased in LR-A (p < 0.05). MMP-12 concentrations also significantly decreased in LR-I (p < 0.05) from baseline concentrations. There were no significant differences between LP-A and LP-I preparations and MMP concentrations. MMP-10 concentrations in all PRP samples compared to each freezing time point were also not significantly different. MMPs regulate components of the extracellular matrix (ECM) in the remodeling phase of musculoskeletal injury. In this study, we observed a significant increase and decrease in MMP concentrations in response to a single freeze-thaw cycle in inactivated PRP and activated PRP preparations. This evidence contributes to the growing body of literature on the optimization of PRP preparation and storage strategies prior to delivery. Our findings suggest that specific PRP preparations after a single freeze-thaw may be more advantageous for certain musculoskeletal applications based on the presence of MMP concentrations.

Platelet-Rich Plasma Releasate Promotes Early Healing in Tendon After Acute Injury

Background

Acute tendon injury can limit motion and thereby inhibit tendon healing. Positive results have been found after the use of platelet-rich plasma (PRP) to treat tendon injury; however, the early effects of PRP on tendon regeneration are not known.

Purpose/Hypothesis

The purpose of this study was to evaluate the effects of PRP releasate (PRPr) on the early stages of tendon healing in a rat partial tenotomy model. It was hypothesized that PRPr can promote early healing of an Achilles tendon in rats.

Study Design

Controlled laboratory study.

Methods

PRP was prepared by a 2-step method of manual platelet concentration from 10 rats. PRPr was isolated from the clotted preparation after activation by thrombin and was applied to an Achilles tendon on 1 side of 30 rats on the second day after partial tenotomy, with normal saline used as the control on the other side. Achilles tendon samples were harvested 5 and 10 days after tenotomy. At each time point, 15 Achilles tendon samples were obtained, of which 5 samples were evaluated by Masson trichrome staining, apoptosis, and cell proliferation, while the other 10 samples were tested for tensile strength using a material testing machine.

Results

Compared with saline-treated control tendons, the PRPr-treated tendons showed increased collagen synthesis near the cut edge and fewer apoptotic cells (P = .01). An immunohistochemical analysis revealed more Ki-67-positive cells but fewer cluster of differentiation (CD) 68⁺ (ED1⁺) macrophages in PRPr tendons compared with saline-treated tendons (P < .01). Tendons treated with PRPr also showed higher ultimate tensile strength than those treated with saline (P = .03).

Conclusion

PRPr treatment promotes tissue recovery in the early phase of tendon healing by stimulating tendon cell proliferation and collagen production while inhibiting cell apoptosis and CD68⁺ (ED1⁺) macrophage infiltration.

Clinical Relevance

These findings suggest that with PRPr treatment, higher loads can be applied to the healing tendon at an earlier time, which can help the patient resume activity earlier.

A Comparison of Growth Factors and Cytokines in Fresh Frozen Plasma and Never Frozen Plasma

BACKGROUND

Fresh frozen plasma (FFP) contains proinflammatory mediators released from cellular debris during frozen storage. In addition, recent studies have shown that transfusion of never-frozen plasma (NFP), instead of FFP, may be superior in trauma patients. We hypothesized that FFP would have higher levels of inflammatory mediators when compared to NFP.

MATERIALS AND METHODS

FFP (n = 8) and NFP (n = 8) samples were obtained from an urban, level 1 trauma center blood bank. The cytokines in these samples were compared using a Milliplex (Milliplex Sigma) human cytokine magnetic bead panel multiplex assay for 41 different biomarkers.

RESULTS

Growth factors that were higher in NFP included platelet-derived growth factor-AA (PDGF-AA; 8.09 versus 108.00 pg/mL, P < 0.001) and PDGF-AB (0.00 versus 215.20, P= 0.004). Soluble CD40-ligand (sCD40L), a platelet activator and pro-coagulant, was higher in NFP (31.81 versus 80.45 pg/mL, P< 0.001). RANTES, a leukocyte chemotactic cytokine was higher in NFP (26.19 versus 1418.00 pg/mL, P< 0.001). Interleukin-4 (5.70 versus 0.00 pg/mL, P= 0.03) and IL-8 (2.20 versus 0.52 pg/ml, P= 0.03) levels were higher in were higher in FFP.

CONCLUSIONS

Frozen storage of plasma may result in decrease of several growth factors and/or pro-coagulants found in NFP. In addition, the freezing and thawing process may induce release of pro-inflammatory chemokines. Further studies are needed to determine if these cytokines result in improved outcomes with NFP over FFP in transfusion of trauma patients.

The Use of Autologous Protein Solution (Pro-Stride®) and Leukocyte-Rich Platelet-Rich Plasma (Restigen®) in Canine Medicine

The use of autologous orthobiologics is an emerging area of interest in veterinary medicine. In this retrospective study, we reviewed the clinical results achieved using two orthobiologics devices to address orthopedic injuries and tissue repair. Leukocyte (White blood cell)-rich platelet-rich plasma (L-PRP) devices produce outputs containing high concentrations of growth factors from venous blood. The Autologous Protein Solution (APS) device produces an orthobiologic containing high concentrations of growth factors and anti-inflammatory cytokines. L-PRP has commonly been used to address soft tissue injuries. APS has been injected into the joint to address osteoarthritis. In the last five years, our practice has treated 35 dogs (38 treatments) with L-PRP and 98 dogs (108 treatments) with APS. Our group has used L-PRP and APS to address orthopedic conditions including osteoarthritis, bursitis, tendinitis, tendon/ligament rupture/repair procedures, post-surgical femoral head osteotomy/tibial-plateau-leveling osteotomy tissue repair, lumbosacral stenosis, patellar luxation, joint laxity, and osteochondral dissecans. The results achieved with L-PRP and APS have been favorable (observed pain improvement and minimal adverse reactions), but sometimes have not achieved complete pain relief or tissue repair. The most common application for L-PRP was patellar luxation and the most common application for APS was injection post-ACL surgery. Canine OA has been successfully managed in several patients with repeat injections of APS over the course of several years. Future studies on specific conditions are ongoing and including efforts to further characterize these products in canine medicine.

Scalable Production of Equine Platelet Lysate for Multipotent Mesenchymal Stromal Cell Culture

Translation of multipotent mesenchymal stromal cell (MSC)-based therapies is advancing in human and veterinary medicine. One critical issue is the in vitro culture of MSC before clinical use. Using fetal bovine serum (FBS) as supplement to the basal medium is still the gold standard for cultivation of many cell types including equine MSC. Alternatives are being explored, with substantial success using platelet lysate-supplemented media for human MSC. However, progress lags behind in the veterinary field. The aim of this study was to establish a scalable protocol for equine platelet lysate (ePL) production and to test the ePL in equine MSC culture. Whole blood was harvested into blood collection bags from 20 healthy horses. After checking sample materials for pathogen contamination, samples from 19 animals were included. Platelet concentrates were prepared using a buffy coat method. Platelets, platelet-derived growth factor BB, and transforming growth factor β1 concentrations were increased in the concentrates compared with whole blood or serum (p < 0.05), while white blood cells were reduced (p < 0.05). The concentrates were lysed using freeze/thaw cycles, which eliminated the cells while growth factor concentrations were maintained. Donor age negatively correlated with platelet and growth factor concentrations after processing (p < 0.05). Finally, all lysates were pooled and the ePL was evaluated as culture medium supplement in comparison with FBS, using adipose-derived MSC from four unrelated donor horses. MSC proliferated well in 10% FBS as well as in 10% ePL. However, using 5 or 2.5% ePL entailed highly inconsistent proliferation or loss of proliferation, with significant differences in generation times and confluencies (p < 0.05). MSC expressed the surface antigens CD90, CD44, and CD29, but CD73 and CD105 detection was low in all culture media. Adipogenic and osteogenic differentiation led to similar results in MSC from different culture media. The buffy coat method is useful to produce equine platelet concentrate with increased platelet and reduced white blood cell content in large scales. The ePL obtained supports MSC expansion similar as FBS when used at the same concentration (10%). Further investigations into equine MSC functionality in culture with ePL should follow.

Regenerative Medicine for Equine Musculoskeletal Diseases

Simple Summary

Lameness due to musculoskeletal disease is the most common diagnosis in equine veterinary practice. Many of these orthopaedic disorders are chronic problems, for which no clinically satisfactory treatment exists. Thus, high hopes are pinned on regenerative medicine, which aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. Some regenerative medicine therapies have already made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising but diverse results. This review summarises the current knowledge of commonly used regenerative medicine treatments and critically discusses their use.

Abstract

Musculoskeletal injuries and chronic degenerative diseases commonly affect both athletic and sedentary horses and can entail the end of their athletic careers. The ensuing repair processes frequently do not yield fully functional regeneration of the injured tissues but biomechanically inferior scar or replacement tissue, causing high reinjury rates, degenerative disease progression and chronic morbidity. Regenerative medicine is an emerging, rapidly evolving branch of translational medicine that aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. It includes tissue engineering but also cell-based and cell-free stimulation of endogenous self-repair mechanisms. Some regenerative medicine therapies have made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising results. However, the qualitative and quantitative spatiotemporal requirements for specific bioactive factors to trigger tissue regeneration in the injury response are still unknown, and consequently, therapeutic approaches and treatment results are diverse. To exploit the full potential of this burgeoning field of medicine, further research will be required and is ongoing. This review summarises the current knowledge of commonly used regenerative medicine treatments in equine patients and critically discusses their use.

Preparation and Evaluation of Sustained Release Platelet-Rich Plasma-Loaded Gelatin Microspheres Using an Emulsion Method

The management and treatment of chronic wounds or acute wounds remain a major challenge in modern medicine. The application of autologous platelet-rich plasma (PRP) has become a promising adjuvant therapy to promote wound healing. PRP is derived from centrifuged whole blood to extract concentrated platelets, and a large amount of cytokines and growth factors are released upon activation. These bioactive molecules can enhance angiogenesis and tissue regeneration. Herein, PRP-loaded gelatin microspheres were prepared by the emulsion cross-linking method. Scanning electron microscopy results showed that the prepared microspheres are completely spherical, with an average particle size of 15.95 ± 3.79 μm and having a uniform particle size. Among them, the surface of a single microsphere is smooth and has a microporous structure, which may be the main channel for drug diffusion. Results of drug release measurements show that the prepared microspheres can slowly release the vascular endothelial growth factor for more than 7 days. In vitro cell experiments show that the prepared microspheres can promote proliferation and migration of L929 mouse fibroblast cells. In summary, the prepared PRP-loaded gelatin microspheres with high and long-term activity can provide experimental and theoretical knowledge for the development of the clinical long-acting injectable formulations.

Optimal activation methods for maximizing the concentrations of platelet-derived growth factor-BB and transforming growth factor-β1 in equine platelet-rich plasma

Platelet-rich plasma (PRP) therapy has been widely applied in various medical fields including humans and horses. This study aimed to establish an optimal activation method to stably and reproducibly maximize the concentrations of platelet-derived growth factor-BB (PDGF-BB) and transforming growth factor-β1 (TGF-β1) contained in equine PRP. Autologous PRP was prepared from 11 Thoroughbreds. For the activation test, PRP was activated by either a single freeze-thaw cycle (Fr) or adding calcium and autologous serum containing thrombin (Ca). PDGF-BB and TGF-β1 concentrations in Fr, Ca, nonactivated (No), and platelet-poor plasma (PPP) samples were determined using ELISA and compared. For repetitive freeze-thaw test, PRP was subjected to single (Fr1), double (Fr2), triple (Fr3), or quadruple (Fr4) freeze-thaw cycles and the concentrations of both growth factors in samples were compared similarly. The PDGF-BB concentration in Ca was significantly higher than that in other preparations. The TGF-β1 concentrations in Fr and Ca were significantly higher than those in PPP and No, with no significant differences between Fr and Ca. The concentrations of both factors were significantly increased in PRP treated with multiple cycles of freeze-thaw compared with that in PRP treated with a single cycle. No significant differences were noted among Fr2, Fr3, and Fr4. Our findings suggest that activation by adding calcium and autologous serum is optimal for instant use of PRP and that double freeze-thawing is an easier and optimal activation method for cryopreserved PRP.

Efficacy of a Semi Automated Commercial Closed System for Autologous Leukocyte- and Platelet-Rich Plasma (l-prp) Production in Dogs: A Preliminary Study

BACKGROUND

To characterize the cellular composition (platelets, erythrocytes, and leukocytes) and determine platelet-derived growth factor isoform BB (PDGF-BB) concentration in canine leukocyte- and platelet rich plasma (L-PRP) produced using a commercial semi-automated closed system.

METHODS

Twenty milliliters of citrated whole blood were obtained from 30 healthy un-sedated canine blood donors and processed using a semi-automated completely closed commercial system (CPUNT 20, Eltek group, Casale Monferrato, Alessandria, Italy) according to the manufacturer's instructions. Erythrocyte, leukocyte, and platelet counts were determined in both whole blood (WB) and resultant L-PRP. The PDGF-BB concentration was evaluated after bovine thrombin activation of 10 L-PRP samples.

RESULTS

This commercial system produced on average 2.3 ± 0.7 mL of L-PRP containing a high concentration of platelets (767,633 ± 291,001 μL, p < 0.001), with a 4.4 fold increase in platelet count, lower concentration of erythrocytes (528,600 ± 222,773 μL, p < 0.001) and similar concentration of leukocytes (8422 ± 6346 μL, p = 0.9918) compared with WB. L-PRP had an average of 3442 ± 2061 pg/mL of PDGF-BB after thrombin activation. Neutrophils, lymphocytes and monocytes average percent content in L-PRP was 14.8 ± 13.2, 71.7 ± 18.5 and 10.7 ± 6.4, respectively.

CONCLUSION

Sterile canine L-PRP prepared using this semi-automated closed system is easy to obtain, produces a significant increase in platelet count compared to WB and contains a detectable concentration of PDGF-BB after activation. Additional in vitro and in vivo studies are needed to assess inflammatory markers concentration and the therapeutic efficacy of this L-PRP in dogs.

Revisiting the Regenerative Therapeutic Advances Towards Erectile Dysfunction

Erectile dysfunction (ED) is an inability to attain or maintain adequate penile erection for successful vaginal intercourse, leading to sexual and relationship dissatisfaction. To combat ED, various surgical and non-surgical approaches have been developed in the past to restore erectile functions. These therapeutic interventions exhibit significant impact in providing relief to patients; however, due to their associated adverse effects and lack of long-term efficacy, newer modalities such as regenerative therapeutics have gained attention due to their safe and prolonged efficacy. Stem cells and platelet-derived biomaterials contained in platelet-rich plasma (PRP) are thriving as some of the major therapeutic regenerative agents. In recent years, various preclinical and clinical studies have evaluated the individual, as well as combined of stem cells and PRP to restore erectile function. Being rich in growth factors, chemokines, and angiogenic factors, both stem cells and PRP play a crucial role in regenerating nerve cells, myelination of axons, homing and migration of progenitor cells, and anti-fibrosis and anti-apoptosis of damaged cavernous nerve in corporal tissues. Further, platelet-derived biomaterials have been proven to be a biological supplement for enhancing the proliferative and differentiation potential of stem cells towards neurogenic fate. Therefore, this article comprehensively analyzes the progresses of these regenerative therapies for ED.