# Exploring Injectable Scaffolded Spheroids for Nucleus Pulposus Therapy in Degenerated Intervertebral Discs

## TL;DR

Researchers developed injectable scaffolded spheroids to improve cell survival and regeneration in degenerated intervertebral discs.

## Contribution

They created injectable tissue-building blocks using 3D-printed microscaffolds and spheroids for nucleus pulposus therapy.

## Key findings

- Scaffolded spheroids maintained high cell viability and produced extracellular matrix under various conditions.
- They upregulated key nucleus pulposus markers like ACAN, KRT18, and HIF1α, indicating successful differentiation.
- S-SPH retained structural integrity and viability after injection, showing potential for in vivo application.

## Abstract

Cell-based therapies for intervertebral disc degeneration
(IVDD)
treatment face significant challenges, including cell damage from
injection-induced shear stress and poor survival in the harsh, nutrient-depleted
microenvironment of the intervertebral disc. To overcome these challenges,
we developed scaffolded spheroids (S-SPH) by integrating human bone
marrow-derived mesenchymal stem cell (hBMSC) spheroids (SPH) into
microscaffolds (MS) produced via high-resolution 3D printing, thereby
forming injectable tissue-building blocks. We optimized cell seeding
density (∼2000 cells/spheroid) and MS fabrication parameters
and induced nucleus pulposus (NP)-like differentiation using growth
differentiation factor-5 (GDF5) under both normoxic and hypoxic, low-glucose
conditions mimicking a healthy in vivo-like environment.
S-SPH maintained high cell viability and produced abundant extracellular
matrix under both culture conditions. They also upregulated key NP
markers, including aggrecan (ACAN), keratin-18 (KRT18), and hypoxia-inducible
factor-1α (HIF1α), which indicated successful NP-like
differentiation. They also exhibited improved compressive properties
approaching those of native human IVD and retained structural integrity
and cell viability following injection through a 26G needle. When
differentiated into an NP-like phenotype, S-SPH fused and retained
a high viability upon injection in vitro. These results
demonstrate that S-SPH provide a promising in vitro strategy for NP regeneration, warranting further preclinical evaluation
for IVDD therapy.