Effect of culture duration on chondrogenic preconditioning of equine bone marrow mesenchymal stem cells in self-assembling peptide hydrogel

Treatment Effects of Intra-Articular Allogenic Mesenchymal Stem Cell Secretome in an Equine Model of Joint Inflammation

Background

Allogenic mesenchymal stem cell (MSC) secretome is a novel intra-articular therapeutic that has shown promise in in vitro and small animal models and warrants further investigation.

Objectives

To investigate if intra-articular allogenic MSC-secretome has anti-inflammatory effects using an equine model of joint inflammation.

Study Design

Randomized positively and negatively controlled experimental study.

Method

In phase 1, joint inflammation was induced bilaterally in radiocarpal joints of eight horses by injecting 0.25 ng lipopolysaccharide (LPS). After 2 h, the secretome of INFy and TNFα stimulated allogeneic equine MSCs was injected in one randomly assigned joint, while the contralateral joint was injected with medium (negative control). Clinical parameters (composite welfare scores, joint effusion, joint circumference) were recorded, and synovial fluid samples were analyzed for biomarkers (total protein, WBCC; eicosanoid mediators, CCL2; TNFα; MMP; GAGs; C2C; CPII) at fixed post-injection hours (PIH 0, 8, 24, 72, and 168 h). The effects of time and treatment on clinical and synovial fluid parameters and the presence of time-treatment interactions were evaluated. For phase 2, allogeneic MSC-secretome vs. allogeneic equine MSCs (positive control) was tested using a similar methodology.

Results

In phase 1, the joint circumference was significantly (p < 0.05) lower in the MSC-secretome treated group compared to the medium control group at PIH 24, and significantly higher peak synovial GAG values were noted at PIH 24 (p < 0.001). In phase 2, no significant differences were noted between the treatment effects of MSC-secretome and MSCs.

Main Limitations

This study is a controlled experimental study and therefore cannot fully reflect natural joint disease. In phase 2, two therapeutics are directly compared and there is no negative control.

Conclusions

In this model of joint inflammation, intra-articular MSC-secretome injection had some clinical anti-inflammatory effects. An effect on cartilage metabolism, evident as a rise in GAG levels was also noted, although it is unclear whether this could be considered a beneficial or detrimental effect. When directly comparing MSC-secretome to MSCs in this model results were comparable, indicating that MSC-secretome could be a viable off-the-shelf alternative to MSC treatment.

Chondroinductive Peptides for Cartilage Regeneration

Inducing and maintaining a hyaline cartilage phenotype is the greatest challenge for cartilage regeneration. Synthetic chondroinductive biomaterials might be the answer to the unmet clinical need for a safe, stable, and cost-effective material capable of inducing true hyaline cartilage formation. The past decade witnessed an emergence of peptides to achieve chondrogenesis, as peptides have the advantages of versatility, high target specificity, minimized toxicity and immunogenicity, and ease of synthesis. Here, we review peptides as the basis for creating promising synthetic chondroinductive biomaterials for in situ scaffold-based cartilage regeneration. We provide a thorough review of peptides evaluated for cartilage regeneration while distinguishing between peptides reported to induce chondrogenesis independently, and peptides reported to act in synergy with other growth factors to induce cartilage regeneration. Additionally, we highlight that most peptide studies have been in vitro, and appropriate controls are not always present. A few rigorously-performed in vitro studies have proceeded to in vivo studies, but the peptides in those in vivo studies were mainly introduced via systemic, subcutaneous, or intraarticular injections, with a paucity of studies employing in situ defects with appropriate controls. Clinical translation of peptides will require the evaluation of these peptides in well-controlled in vivo cartilage defect studies. In the decade ahead, we may be poised to leverage peptides to design devices that are safe, reproducible, cost-efficient, and scalable biomaterials, which are themselves chondroinductive to achieve true hyaline cartilage regeneration without the need for growth factors and other small molecules.

Human nasal septal chondrocytes (NSCs) preconditioned on NSC-derived matrix improve their chondrogenic potential

Background

Extracellular matrix (ECM) has a profound effect on cell behaviors. In this study, we prepare a decellularized human nasal septal chondrocyte (NSC)-derived ECM (CHDM), as a natural (N-CHDM) or soluble form (S-CHDM), and investigate their impact on NSCs differentiation.

Methods

N-CHDM, S-CHDM were obtained from NSC. To evaluate function of NSC cultured on each substrate, gene expression using chondrogenic marker, and chondrogenic protein expression were tested. Preconditioned NSCs-loaded scaffolds were transplanted in nude mice for 3 weeks and analyzed.

Results

When cultivated on each substrate, NSCs exhibited similar cell spread area but showed distinct morphology on N-CHDM with significantly lower cell circularity. They were highly proliferative on N-CHDM than S-CHDM and tissue culture plastic (TCP), and showed more improved cell differentiation, as assessed via chondrogenic marker (Col2, Sox9, and Aggrecan) expression and immunofluorescence of COL II. We also investigated the effect of NSCs preconditioning on three different 2D substrates while NSCs were isolated from those substrates, subsequently transferred to 3D mesh scaffold, then cultivated them in vitro or transplanted in vivo. The number of cells in the scaffolds was similar to each other at 5 days but cell differentiation was notably better with NSCs preconditioned on N-CHDM, as assessed via real-time q-PCR, Western blot, and immunofluorescence. Moreover, when those NSCs-loaded polymer scaffolds were transplanted subcutaneously in nude mice for 3 weeks and analyzed, the NSCs preconditioned on the N-CHDM showed significantly advanced cell retention in the scaffold, more cells with a chondrocyte lacunae structure, and larger production of cartilage ECM (COL II, glycosaminoglycan).

Conclusions

Taken together, a natural form of decellularized ECM, N-CHDM would present an advanced chondrogenic potential over a reformulated ECM (S-CHDM) or TCP substrate, suggesting that N-CHDM may hold more diverse signaling cues, not just limited to ECM component.

ChondroGELesis: Hydrogels to harness the chondrogenic potential of stem cells

The extracellular matrix is a highly complex microenvironment, whose various components converge to regulate cell fate. Hydrogels, as water-swollen polymer networks composed by synthetic or natural materials, are ideal candidates to create biologically active substrates that mimic these matrices and target cell behaviour for a desired tissue engineering application. Indeed, the ability to tune their mechanical, structural, and biochemical properties provides a framework to recapitulate native tissues. This review explores how hydrogels have been engineered to harness the chondrogenic response of stem cells for the repair of damaged cartilage tissue. The signalling processes involved in hydrogel-driven chondrogenesis are also discussed, identifying critical pathways that should be taken into account during hydrogel design.

3D cell-printing of biocompatible and functional meniscus constructs using meniscus-derived bioink

Meniscus injuries are prevalent in orthopedic diagnosis. The reconstruction of the structural inhomogeneity and anisotropy of the meniscus is a major challenge in clinical practice. Meniscal tissue engineering has emerged as a potential alternative for the treatment of various meniscal diseases and injuries. In this study, we developed three-dimensional (3D) cell-printed meniscus constructs using a mixture of polyurethane and polycaprolactone polymers and cell-laden decellularized meniscal extracellular matrix (me-dECM) bioink with high controllability and durable architectural integrity. The me-dECM bioink provided 3D cell-printed meniscus constructs with a conducive biochemical environment that supported growth and promoted the proliferation and differentiation of encapsulated stem cells toward fibrochondrogenic commitment. In addition, we investigated the in vivo performance of the 3D cell-printed meniscus constructs, which exhibited biocompatibility, excellent mechanical properties, and improved biological functionality. These attributes were similar to those of the native meniscus. Collectively, the 3D cell-printing technology and me-dECM bioink facilitate the recapitulation of meniscus tissue specificity in the aspect of the shape and microenvironment for meniscus regeneration. Further, the developed constructs can potentially be applied in clinical practice.

Peptide Self-Assembly into Hydrogels for Biomedical Applications Related to Hydroxyapatite

Amphiphilic peptides can be self-assembled by establishing physical cross-links involving hydrogen bonds and electrostatic interactions with divalent ions. The derived hydrogels have promising properties due to their biocompatibility, reversibility, trigger capability, and tunability. Peptide hydrogels can mimic the extracellular matrix and favor the growth of hydroxyapatite (HAp) as well as its encapsulation. Newly designed materials offer great perspectives for applications in the regeneration of hard tissues such as bones, teeth, and cartilage. Furthermore, development of drug delivery systems based on HAp and peptide self-assembly is attracting attention.