Oral Presentation: Injectable biomimetic hydrogel supports cell delivery for nucleus pulposus regeneration in dynamic bovine organ culture
Description
52nd Annual Meeting of the International Society for the Study of the Lumbar Spine (ISSLS)
Cape Town, South Africa
Cape Town, South Africa
Abstract
Introduction: Low back pain is one of the leading causes of disability worldwide, affecting over 568 million people. It is primarily associated with degenerative disc disease (DDD), characterized by loss of water and proteoglycans in the nucleus pulposus (NP). These changes reduce disc height and alter spinal biomechanics, resulting in chronic pain. Current treatments primarily focus on symptomatic relief rather than restoration of disc function. Therefore, an effective and durable therapeutic approach must address both the mechanical integrity and the biochemical microenvironment of the IVD. In this study, we present the development of an injectable biomimetic hydrogel composed of hyaluronic acid (HA), collagen type II (COLII), and silk fibroin (SF) microfibers, designed to emulate the native NP microenvironment and provide the mechanical resilience necessary for functional disc repair.
Methods: The system gelifies in situ upon injection, creating a mechano-biological structure suitable for cell delivery. Bone marrow–derived mesenchymal stromal cells (BMSCs) were encapsulated within HA/COLII and HA/COLII/SF hydrogels to assess cell viability and cytoskeletal structure using calcian AM/ethidium homodimer-1 and phalloidin/4',6-diamidino-2-phenylindole (DAPI) staining, respectively. Degenerated bovine IVD explants were generated by papain injection and subsequently treated with the hydrogels using a custom dual-syringe injector (Figure 1B-i). The hydrogel distribution within the disc was visualized by micro-computed tomography (µCT) by adding ZrO₂ to the hydrogels as a contrast agent. To mimic physiological conditions, discs were cultured in a custom-built bioreactor that applied cyclic compression (0.2 ± 0.1 MPa, 0.2 Hz) and torsion (±2°, 0.05 Hz) daily for 1.5 h over one week (Figure 1C).
Results: Live/dead staining indicated high cell viability across both hydrogel formulations; the red appearance of silk fibroin fibers resulted from nonspecific binding of ethidium homodimer-1 (Figure 1A-i), while phalloidin/DAPI staining revealed progressive actin filament organization and network formation over 15 days (Figure 1A-ii). µCT confirmed homogeneous hydrogel filling within the NP region post-injection (Figure 1B-ii). Macroscopic examination revealed improved tissue integrity and mechanical stability (Figure 1D-i). MRI analysis further demonstrated that hydrogel-treated IVDs retained hydration and height under dynamic loading compared to papain-degenerated controls (Figures 1D-ii and 1D-iii).
Discussion: This study demonstrated that injectable HA/COLII/SF hydrogels served as an effective carrier for stem cell delivery and promoted structural restoration in dynamically loaded IVD organ cultures. The system offers a promising platform for studying minimally invasive regenerative therapies targeting DDD.
Keywords: Intervertebral disc regeneration, injectable hydrogel, dynamic bioreactor.
Methods: The system gelifies in situ upon injection, creating a mechano-biological structure suitable for cell delivery. Bone marrow–derived mesenchymal stromal cells (BMSCs) were encapsulated within HA/COLII and HA/COLII/SF hydrogels to assess cell viability and cytoskeletal structure using calcian AM/ethidium homodimer-1 and phalloidin/4',6-diamidino-2-phenylindole (DAPI) staining, respectively. Degenerated bovine IVD explants were generated by papain injection and subsequently treated with the hydrogels using a custom dual-syringe injector (Figure 1B-i). The hydrogel distribution within the disc was visualized by micro-computed tomography (µCT) by adding ZrO₂ to the hydrogels as a contrast agent. To mimic physiological conditions, discs were cultured in a custom-built bioreactor that applied cyclic compression (0.2 ± 0.1 MPa, 0.2 Hz) and torsion (±2°, 0.05 Hz) daily for 1.5 h over one week (Figure 1C).
Results: Live/dead staining indicated high cell viability across both hydrogel formulations; the red appearance of silk fibroin fibers resulted from nonspecific binding of ethidium homodimer-1 (Figure 1A-i), while phalloidin/DAPI staining revealed progressive actin filament organization and network formation over 15 days (Figure 1A-ii). µCT confirmed homogeneous hydrogel filling within the NP region post-injection (Figure 1B-ii). Macroscopic examination revealed improved tissue integrity and mechanical stability (Figure 1D-i). MRI analysis further demonstrated that hydrogel-treated IVDs retained hydration and height under dynamic loading compared to papain-degenerated controls (Figures 1D-ii and 1D-iii).
Discussion: This study demonstrated that injectable HA/COLII/SF hydrogels served as an effective carrier for stem cell delivery and promoted structural restoration in dynamically loaded IVD organ cultures. The system offers a promising platform for studying minimally invasive regenerative therapies targeting DDD.
Keywords: Intervertebral disc regeneration, injectable hydrogel, dynamic bioreactor.
Date Issued
2026
Publication Type
Conference Item
Language(s)
en
Author(s)
Abdekhodaie, M. | |
Wöltje, M. |
Related Collection(s)
Access(Rights)
open.access