Table 3.
Studies reporting the use of peptide hydrogels as 3D scaffolds for IVD repair.
| Hydrogel | Injectable? | Cell Type | Duration | Outcomes | Refs. |
|---|---|---|---|---|---|
| RKP (RADA16 functionalised with KPSS) | N/A | Human NP-derived stem cells | 2 days | High cell proliferation and upregulation of the gene expression of collagen II, aggrecan, and Sox-9 compared to controls | [224] |
| RADA16:RADA-KPSS in 1:1 ratio | Yes | Human MSCs | 14 days | Hydrogels promoted cell proliferation and chemotaxis as well as kept cell viability up to 14 days once injected into an ex vivo cultured disc mode | [227] |
| RAD-RKP (co-assembly of RADA16 with RKP) | Yes | Degenerated human NP cells | 28 days | High cell proliferation and migration. Collagen type II, SOX9, and aggrecan were upregulated, while collagen I was downregulated compared to controls | [228] |
| LN-NS (co-assembly of link N-conjugated RADA16 with RADA16) | Yes | Rabbit NP cells | 14 days | High viability and cell adhesion. Increased gene expression of PGs and collagen type II compared to controls | [230] |
| LN-NS (1:1 mixture of link N-conjugated RADA16 with RADA16) | Yes | Rabbit Notochordal Cells | 14 days | High cell survival rate. Increased gene expression of aggrecan and collagen type II compared to controls | [231] |
| KLD12 | Yes | Rabbit NP cells | 14 days | Increased GAG and collagen type II production over time. NP cells preserved high viability and characteristic shape | [232] |
| KLD12/TGF-β1 | N/A | Rabbit MSCs | 14 days | High cell viability over time. Increased gene expression and protein deposition of aggrecan and collagen type II compared to controls | [190] |
| FEFEFKFK | Yes | Bovine NP Cells | 14 days | Characteristic morphology and high viability over time. Upregulation of collagen type II, aggrecan, cytokeratin-8, cytokeratin-18, SOX9, and FOXF1, CA12 | [195] |
| FEFKFEFK-GO | Yes | Bovine NP cells | 7 days | Increased viability of NP cells and stable metabolic activity over time | [233] |
| FEFKFEFK-(GO + TGF-β3) | Yes | Bovine NP cells | 21 days | TGF-β3-decorated GO flakes induced increased gene expression and matrix deposition over time compared to TGF-β3 ‘free’ in peptide hydrogels or added exogenously. SMAD signalling was preserved when TGF-β3 was anchored on GO flakes, inducing ECM production | [234] |
| Ac-ID3, Ac-LD6, Ac-AD6 | N/A | Porcine NP cells | 2 days | Porcine NP cells showed good viability when incubated with peptides | [235] |
| Col-PA/E-PA (PA hydrogel decorated with collagen-mimic POG motif) | Yes | Rat MSCs | 14 days | In vitro differentiation into NP-like cells. Increased GAGs and collagen deposition compared to controls. Functional recovery of rabbit IVDs after injection in vivo | [236] |
| PuraMatrix® | Yes | Human MSCs | 21 days | High deposition of GAGs accompanied by fast stress relaxation and mechanical properties mimicking native NP tissue | [237] |
| Elastin-like polypeptide/thiol-modified hyaluronan | Yes | Human IVD cells | 21 days | High cell viability and maintenance of anabolic cell phenotype. Good biocompatibility in a preclinical rabbit annular puncture model | [238] |
| P11-4, P11-8, P11-9, P11-12/chondroitin sulphate |
Yes | Ex vivo bovine caudal spine model | 1 day | Hybrid hydrogels showed mechanical properties similar to the human NP. Hydrogels injected in a caudal spine model undergo gelation in situ with minimal leakage over time | [239] |