Mussel inspired injectable chitosan hydrogel modified with catechol for cell adhesion and cartilage defect repair

Repairing articular cartilage defect is a great challenge due to the poor self-regenerative capability of cartilage. Hydrogel-based tissue engineering has been considered as an effective strategy. In this study, inspired...

Zonal-Layered Chondrocyte Sheets for Repairment of Full-Thickness Articular Cartilage Defect: A Mini-Pig Model

The cell sheet technique is a promising approach for tissue engineering, and the present study is aimed to determine a better configuration of cell sheets for cartilage repair. For stratified chondrocyte sheets (S-CS), articular chondrocytes isolated from superficial, middle, and deep zones were stacked accordingly. Heterogeneous chondrocyte sheets (H-CS) were obtained by mixing zonal chondrocytes. The expressions of chondrocytes, cytokine markers, and glycosaminoglycan (GAG) production were assessed in an in vitro assay. The curative effect was investigated in an in vivo porcine osteochondral defect model. The S-CS showed a higher cell viability, proliferation rate, expression of chondrogenic markers, secretion of tissue inhibitor of metalloproteinase, and GAG production level than the H-CS group. The expressions of ECM destruction enzyme and proinflammatory cytokines were lower in the S-CS group. In the mini-pigs articular cartilage defect model, the S-CS group had a higher International Cartilage Repair Society (ICRS) macroscopic score and displayed a zonal structure that more closely resembled the native cartilage than those implanted with the H-CS. Our study demonstrated that the application of the S-CS increased the hyaline cartilage formation and improved the surgical outcome of chondrocyte implication, offering a better tissue engineering strategy for treating articular cartilage defects.

Culture Time Needed to Scale up Infrapatellar Fat Pad Derived Stem Cells for Cartilage Regeneration: A Systematic Review

Adipose tissue is a rich source of stem cells, which are reported to represent 2% of the stromal vascular fraction (SVF). The infrapatellar fat pad (IFP) is a unique source of tissue, from which human adipose-derived stem cells (hADSCs) have been shown to harbour high chondrogenic potential. This review aims to calculate, based on the literature, the culture time needed before an average knee articular cartilage defect can be treated using stem cells obtained from arthroscopically or openly harvested IFP. Firstly, a systematic literature review was performed to search for studies that included the number of stem cells isolated from the IFP. Subsequent analysis was conducted to identify the amount of IFP tissue harvestable, stem cell count and the overall yield based on the harvesting method. We then determined the minimum time required before treating an average-sized knee articular cartilage defect with IFP-derived hADSCs by using our newly devised equation. The amount of fat tissue, the SVF cell count and the stem cell yield are all lower in arthroscopically harvested IFP tissue compared to that collected using arthrotomy. As an extrapolation, we show that an average knee defect can be treated in 20 or 17 days using arthroscopically or openly harvested IFP-derived hADSCs, respectively. In summary, the systematic review conducted in this study reveals that there is a higher amount of fat tissue, SVF cell count and overall yield (cells/volume or cells/gram) associated with open (arthrotomy) compared to arthroscopic IFP harvest. In addition to these review findings, we demonstrate that our novel framework can give an indication about the culture time needed to scale up IFP-derived stem cells for the treatment of articular cartilage defects based on harvesting method.

Cartilage Tissue-Mimetic Pellets with Multifunctional Magnetic Hyaluronic Acid-Graft-Amphiphilic Gelatin Microcapsules for Chondrogenic Stimulation

Articular cartilage defect is a common disorder caused by sustained mechanical stress. Owing to its nature of avascular, cartilage had less reconstruction ability so there is always a need for other repair strategies. In this study, we proposed tissue-mimetic pellets composed of chondrocytes and hyaluronic acid-graft-amphiphilic gelatin microcapsules (HA-AGMCs) to serve as biomimetic chondrocyte extracellular matrix (ECM) environments. The multifunctional HA-AGMC with specific targeting on CD44 receptors provides excellent structural stability and demonstrates high cell viability even in the center of pellets after 14 days culture. Furthermore, with superparamagnetic iron oxide nanoparticles (SPIOs) in the microcapsule shell of HA-AGMCs, it not only showed sound cell guiding ability but also induced two physical stimulations of static magnetic field(S) and magnet-derived shear stress (MF) on chondrogenic regeneration. Cartilage tissue-specific gene expressions of Col II and SOX9 were upregulated in the present of HA-AGMC in the early stage, and HA-AGMC+MF+S held the highest chondrogenic commitments throughout the study. Additionally, cartilage tissue-mimetic pellets with magnetic stimulation can stimulate chondrogenesis and sGAG synthesis.