Platelet Lysate-Loaded Photocrosslinkable Hyaluronic Acid Hydrogels for Periodontal Endogenous Regenerative Technology

Abstract

The integrity and function of the periodontium can be compromised by traumatic injuries or periodontitis. Currently available clinical therapies are able to stop the progression of periodontitis and allow the healing of periodontal tissue. However an optimal strategy capable of restoring the anatomy and functionality of the lost periodontal tissue is still to be achieved. This injectable system is based on a photocrosslinkable hydrogel, prepared from methacrylated Hyaluronic Acid (me-HA) and incorporating Platelet Lysate (PL). The delivery of growth factors and cells in situ is expected to enhance regeneration of the periodontium. Various formulations of me-HA containing increasing PL concentrations were studied for achieving the formation of stable photocrosslinkable hydrogels. The produced hydrogels were subsequently characterized to assess mechanical properties, degradation, protein/growth factor release profile, antimicrobial activity and response towards human Periodontal Ligament fibroblasts (hPDLFs). The results demonstrated that it was possible to obtain stable photocrosslinkable hydrogels incorporating different amounts of PL that can be released in a sustained manner. Furthermore, the incorporation of PL improved (p<0.02) the viscoelastic properties of the hydrogels and enhanced their resilience to the degradation by hyaluronidase (HAase). Additionally, the PL showed to provide antimicrobial properties.Finally, hPDLFs, either seeded or encapsulated into the developed hydrogels, showed enhanced proliferation over time (p<0.05), proportionally to the increasing amounts of PL present in the hydrogel formulations.

Hyaluronic acid hydrogels incorporating platelet lysate enhance human pulp cell proliferation and differentiation

“…High molecular weight (1.5-1.8 MDa) hyaluronic acid (HA; S. equii, Sigma-Aldrich, Missouri, USA) was methacrylated following a previously stablished protocol [18,19,28]. In brief, 1% (w/v) HA solution (in distilled water) was reacted with methacrylic anhydride (10 times molar excess) at pH 8.0-8.5, adjusted with NaOH 5 M (Sigma-Aldrich, Missouri, USA), at 4°C.…”

“…HA is a glycosaminoglycan, composed by units of Dglucuronic acid and N-acetyl-D-glucosamine acid [14], and is present in the central region of pulp were the undifferentiated cells are located [15]. HA suitability for regenerative medicine purposes relates with its biocompatibility and ability to be modified through both its carboxyl [16,17] and hydroxyl groups [18,19] to produce stable hydrogels. It has been shown to be suitable for endodontic regenerative procedures, displaying immunomodulatory, and proangiogenic features [4].…”

“…It has been shown to be suitable for endodontic regenerative procedures, displaying immunomodulatory, and proangiogenic features [4]. Moreover, the methacrylation of HA on its hydroxyl moieties, allows the production of injectiqable photocrosslinkable HA hydrogels [18,20]. These injectable hydrogels are ideal for endodontic regenerative approaches as they can easily penetrate throughout the root canal system and crosslink upon specific light activation.…”

“…It is obtained by the simple disruption of the membranes of platelets contained in platelet concentrates by freeze-drying cycles and has been proposed to be more effective and reliable in comparison with the PRHds activated with thrombin or calcium (e.g., PRP) [22,23]. The incorporation of PL into HA hydrogels has been shown to enhance the adhesion and proliferation of human adipose tissue derived cells (hASCs), and periodontal ligament fibroblasts [18,19]. Among the GFs present in PL are the FGF, VEGF, PDGF, TGF-β1, TGF-β2, and IGF [21,22] which are known to promote the formation of tertiary dentin and dental pulp repair [24].…”

“…Moreover, the chemotactic and proangiogenic GFs present in PL (PDGF and VEGF) [25], can facilitate the recruitment of progenitor cells from the amputated pulp tissues. Additionally, the antimicrobial properties exhibited by PL [18,26] might reduce the recurrence of endodontic diseases. However, the effect of human PL associated with biomaterials has not yet been evaluated in human dental pulp cell cultures.…”