Exploring Equine Platelet Lysate as an Allogeneic Orthobiologic: Preclinical Insights into Therapeutic Potential

• Grant number: 25/16975-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: September 01, 2025
• End date: July 31, 2027
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Raquel Yvonne Arantes Baccarin
• Grantee: Sarah Raphaela Torquato Seidel
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 24/20820-7 - EFFICACY AND EFFECTIVENESS OF ALLOGENIC PLATELET LYSATE ON EQUINE JOINT TISSUE: IN VITRO, LABORATORY AND CLINICAL ASPECTS., AP.R

Abstract

The use of orthobiologics, such as Platelet-Rich Plasma (PRP), has already been established in equine medicine for several years; however, it continues to face certain limitations ranging from the high variability of protocols to clinical outcomes that sometimes diverge from those observed in clinical trials. Platelet Lysate (PL), an orthobiologic that can be obtained from platelet concentrates such as PRP, emerges as a new therapeutic alternative. Its acellular nature opens perspectives for allogeneic application, allowing the selection of healthy donors for its production. In addition, PL retains molecular characteristics similar to its PRP origin, presenting high concentrations of growth factors (GF) and anti-inflammatory cytokines, antimicrobial potential, and the advantage of being stored at -20°C, which enables the production of larger volumes, sterility testing prior to use, and the practicality of providing a biological therapy that can be thawed when needed. Thus, this study aims to evaluate its anti-inflammatory and antimicrobial potential, its effects on joint tissues, and its possible cytotoxicity and immunogenicity in preclinical studies. To this end, autologous, allogeneic, and pooled PL will be produced and characterized for the presence of GFs of known relevance to the joint environment (TGF-¿1, PDGF-BB, and IGF-1), eicosanoid (PGE2), and pro- and anti-inflammatory cytokines (IL-1¿, IL-6, IL-10, and TNF-¿). Co-cultures containing cartilage explants and synovial membrane-derived cells from healthy joints will be stimulated with lipopolysaccharide from Escherichia coli (LPS, 100 ng/mL) and treated with either culture medium supplemented or allogeneic PL. Resulting supernatants will be assessed for the presence of TGF-¿1, PGE2, IL-1¿, IL-6, IL-10, and TNF-¿, as well as joint metabolism markers (C-telopeptide of type II collagen, hyaluronic acid, and chondroitin sulfate), while explants will be processed and evaluated histologically and through Scanning Electron Microscopy, to measure anti-inflammatory and chondroprotective activity. Macrophage cultures derived from mononuclear cells will be stimulated with IL-1¿ (10 ng/mL) and treated with autologous or pooled PL. One well from each treatment will be used for cytotoxicity evaluation through the MTT assay; supernatants will be analyzed for immunogenicity via HLA-DRA measurement, and macrophages will undergo RNA extraction and gene sequencing to provide a comprehensive assessment of the immunomodulatory properties of the evaluated therapies. Synovial fluid cultures obtained from healthy joints will be stimulated with Staphylococcus aureus (10¿ CFU/well) and treated with Ringer's lactate or pooled PL. After incubation, the contents of each well (control or treated) will be plated onto Mannitol Salt Agar plates for colony detection and quantification, thereby evaluating the antimicrobial activity against the tested pathogen.