Chondrogenesis of Adipose-Derived Stem Cells Using an Arrayed Spheroid Format

Objective

The chondrogenic response of adipose-derived stem cells (ASCs) is often assessed using 3D micromass protocols that use upwards of hundreds of thousands of cells. Scaling these systems up for high-throughput testing is technically challenging and wasteful given the necessary cell numbers and reagent volumes. However, adopting microscale spheroid cultures for this purpose shows promise. Spheroid systems work with only thousands of cells and microliters of medium.

Methods

Molded agarose microwells were fabricated using 2% w/v molten agarose and then equilibrated in medium prior to introducing cells. ASCs were seeded at 50, 500, 5k cells/microwell; 5k, 50k, cells/well plate; and 50k and 250k cells/15 mL centrifuge tube to compare chondrogenic responses across spheroid and micromass sizes. Cells were cultured in control or chondrogenic induction media. ASCs coalesced into spheroids/pellets and were cultured at 37 °C and 5% CO2 for 21 days with media changes every other day.

Results

All culture conditions supported growth of ASCs and formation of viable cell spheroids/micromasses. More robust growth was observed in chondrogenic conditions. Sulfated glycosaminoglycans and collagen II, molecules characteristics of chondrogenesis, were prevalent in both 5000-cell spheroids and 250,000-cell micromasses. Deposition of collagen I, characteristic of fibrocartilage, was more prevalent in the large micromasses than small spheroids.

Conclusions

Chondrogenic differentiation was consistently induced using high-throughput spheroid formats, particularly when seeding at cell densities of 5000 cells/spheroid. This opens possibilities for highly arrayed experiments investigating tissue repair and remodeling during or after exposure to drugs, toxins, or other chemicals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-022-00746-8.

Chondrocyte death involvement in osteoarthritis

Chondrocyte apoptosis is known to contribute to articular cartilage damage in osteoarthritis and is correlated to a number of cartilage disorders. Micromass cultures represent a convenient means for studying chondrocyte biology, and, in particular, their death. In this review, we focused the different kinds of chondrocyte death through a comparison between data reported in the literature. Chondrocytes show necrotic features and, occasionally, also apoptotic features, but usually undergo a new form of cell death called Chondroptosis, which occurs in a non-classical manner. Chondroptosis has some features in common with classical apoptosis, such as cell shrinkage, chromatin condensation, and involvement, not always, of caspases. The most crucial peculiarity of chondroptosis relates to the ultimate elimination of cellular remnants. Independent of phagocytosis, chondroptosis may serve to eliminate cells without inflammation in situations in which phagocytosis would be difficult. This particular death mechanism is probably due to the unusual condition chondrocytes both in vivo and in micromass culture. This review highlights on the morpho-fuctional alterations of articular cartilage and focus attention on various types of chondrocyte death involved in this degeneration. The death features have been detailed and discussed through in vitro studies based on tridimensional chondrocyte culture (micromasses culture). The study of this particular mechanism of cartilage death and the characterization of different biological and biochemical underlying mechanisms can lead to the identification of new potentially therapeutic targets in various joint diseases.

The micromass formation potential of human adipose-derived stromal cells isolated from different various origins

BACKGROUND

Adult stem cells appear to be a promising subject for tissue engineering, representing an individual material for regeneration of aged and damaged cells. Especially adipose derived stromal cells (ADSC), which are easily to achieve, allow an encouraging perspective due to their capability of differentiating into miscellaneous cell types. Here we describe the in vitro formation of human subcutaneous, visceral and omental ADSC micromasses and compare their histological attributes while being cultivated on collagen membranes.

METHODS

Subcutaneous, visceral and omental fat tissue derived cells were isolated and processed according to standard protocols. Positively stained cells for CD13, CD44 and CD90 were cultivated on agarose in order to study micromass formation using a special method of cell tracking. Stained paraffin-embedded micromasses were analysed morphologically before and after being plated on collagen membranes.

RESULTS

The micromass formation process was similar in all three tissue types. Subcutaneous fat tissue derived micromasses turned out to develop a more homogeneous and compact shape than visceral and omental tissue. Nevertheless all micromasses adhered to collagen membranes with visible spreading of cells. The immune histochemical (IHC) staining of subcutaneous, visceral and omental ADSC micromasses shows a constant expression of CD13 and a decrease of CD44 and CD 90 expression within 28 days. After that period, omental fat cells don't show any expression of CD44.

CONCLUSION

In conclusion micromass formation and cultivation of all analysed fat tissues can be achieved, subcutaneous cells appearing to be the best material for regenerative concepts.

Using primary organotypic mouse midbrain cultures to examine developmental neurotoxicity of silver nanoparticles across two genetic strains

Micromass culture systems have been developed as three-dimensional organotypic in vitro alternatives to test developmental toxicity. We have optimized a murine-based embryonic midbrain micromass system in two genetic strains to evaluate neurodevelopmental effects of gold-cored silver nanoparticles (AgNPs) of differing sizes and coatings-20 nm AgCitrate, 110 nm AgCitrate, and 110 nm AgPVP. AgNPs are increasingly used in consumer, commercial, and medical products for their antimicrobial properties and observations of Ag in adult and fetal brain following in vivo exposures to AgNPs have led to concerns about the potential for AgNPs to elicit adverse effects on neurodevelopment and neurological function. Cytotoxicity was assessed at three time points of development by both nominal dose and by dosimetric dose. Ag dosimetry was assessed in cultures and the gold core component of the AgNPs was used as a tracer for determination of uptake of intact AgNPs and silver dissolution from particles in the culture system. Results by both nominal and dosimetric dose show cell death increased significantly in a dose-dependent manner at later time points (days 15 and 22 in vitro) that coincide with differentiation stages of development in both strains. When assessed by dosimetric dose, cultures were more sensitive to smaller particles, despite less uptake of Ag in smaller particles in both strains.

Mesenchymal stem cell-derived extracellular matrix enhances chondrogenic phenotype of and cartilage formation by encapsulated chondrocytes in vitro and in vivo

Mesenchymal stem cell derived extracellular matrix (MSC-ECM) is a natural biomaterial with robust bioactivity and good biocompatibility, and has been studied as a scaffold for tissue engineering. In this investigation, we tested the applicability of using decellularized human bone marrow derived MSC-ECM (hBMSC-ECM) as a culture substrate for chondrocyte expansion in vitro, as well as a scaffold for chondrocyte-based cartilage repair. hBMSC-ECM deposited by hBMSCs cultured on tissue culture plastic (TCP) was harvested, and then subjected to a decellularization process to remove hBMSCs. Compared with chondrocytes grown on TCP, chondrocytes seeded onto hBMSC-ECM exhibited significantly increased proliferation rate, and maintained better chondrocytic phenotype than TCP group. After being expanded to the same cell number and placed in high-density micromass cultures, chondrocytes from the ECM group showed better chondrogenic differentiation profile than those from the TCP group. To test cartilage formation ability, composites of hBMSC-ECM impregnated with chondrocytes were subjected to brief trypsin treatment to allow cell-mediated contraction, and folded to form 3-dimensional chondrocyte-impregnated hBMSC-ECM (Cell/ECM constructs). Upon culture in vitro in chondrogenic medium for 21 days, robust cartilage formation was observed in the Cell/ECM constructs. Similarly prepared Cell/ECM constructs were tested in vivo by subcutaneous implantation into SCID mice. Prominent cartilage formation was observed in the implanted Cell/ECM constructs 14 days post-implantation, with higher sGAG deposition compared to controls consisting of chondrocyte cell sheets. Taken together, these findings demonstrate that hBMSC-ECM is a superior culture substrate for chondrocyte expansion and a bioactive matrix potentially applicable for cartilage regeneration in vivo.

STATEMENT OF SIGNIFICANCE

Current cell-based treatments for focal cartilage defects face challenges, including chondrocyte dedifferentiation, need for xenogenic scaffolds, and suboptimal cartilage formation. We present here a novel technique that utilizes adult stem cell-derived extracellular matrix, as a culture substrate and/or encapsulation scaffold for human adult chondrocytes, for the repair of cartilage defects. Chondrocytes cultured in stem cell-derived matrix showed higher proliferation, better chondrocytic phenotype, and improved redifferentiation ability upon in vitro culture expansion. Most importantly, 3-dimensional constructs formed from chondrocytes folded within stem cell matrix manifested excellent cartilage formation both in vitro and in vivo. These findings demonstrate the suitability of stem cell-derived extracellular matrix as a culture substrate for chondrocyte expansion as well as a candidate bioactive matrix for cartilage regeneration.

Diabetes-induced effects on cardiomyocytes in chick embryonic heart micromass and mouse embryonic D3 differentiated stem cells

Diabetes mellitus during pregnancy is a considerable medical challenge, since it is related to ‎augmented morbidity and mortality concerns for both the fetus ‎and the pregnant woman. Records show that the etiology of diabetic ‎embryopathy is complicated, as many teratological factors might be involved ‎in the mechanisms of diabetes mellitus-induced congenital malformation. ‎In this study, the potential cardiotoxic effect of hyperglycemia with hyperketonemia was investigated by using two in vitro models; primary chick embryonic cardiomyocytes and stem cell derived cardiomyocytes, where adverse effects were recorded in both systems. The cells were evaluated by changes in beating activity, cell activity, protein content, ROS production, DNA damage and differentiating stem cell migration. The diabetic formulae used produced an increase in DNA damage and a decline in cell migration in mouse embryonic stem cells. These results provide an additional insight into adverse effects during gestational diabetes mellitus and a recommendation for expectant mothers and maternity staff to monitor glycaemic levels months ahead of conception. This study also supports the recommendation of using antioxidants during pregnancy to prevent DNA damage by the production of ROS, which might result in heart defects as well as other developmental anomalies.

Evaluation of embryotoxic potential of olaquindox and vitamin a in micromass culture and in rats

Limb bud (LB) and central nerve system (CNS) cells were prepared from 12.5 day old pregnant female Crj:CD (SD) rats and treated with olaquindox and vitamin A. Cytotoxicity and inhibition on differentiation were measured in each cell. Three doses of olaquindox (4, 21 and 100 mgkg) , and 0.2 and 75 mg/kg of vitamin A were administered to pregnant rat for 11 days from 6(th) to 16(th) of pregnancy. IC50 values of olaquindox for proliferation and differentiation in CNS cell were 22.74 and 28.32 μg/ml and 79.34 and 23.29 μg/ml in LB cell and those values of vitamin A were 8.13 and 5.94 μg/ml in CNS cell and 0.81 and 0.05 μg/ml in LB cell, respectively. Mean body weights of pregnant rats were decreased at high dose of olaquindox (110 mg/kg) but relative ovary weight, number of corpus lutea, and number of implantation were not changed. Resorption and dead fetus were increased at high dose of olaquindox, and relative ovary weight, the number of corpus lutea and implantation, and sex ratio of male to female were not significantly changed in all dose of olaquindox. Mean fetal and placenta weights were significantly (p < 0.01) decreased in rats of high group. Seven fetuses out of 103 showed external anomaly like bent tail, and 10 out of 114 fetuses showed visceral anomalies at high group. The ossification of sternebrae and metacarpals were significantly (p < 0.01) increased by low and middle dose of olaquindox but it was significantly (p < 0.01) prohibited by high dose of olaquindox. In rats treated with vitamin A, the resorption and dead fetus were increased by high dose. Mean fetal weights were significantly (p < 0.01) increased by low dose but significantly (p < 0.01) decreased by high dose. Thirty four fetuses out of 52 showed external anomaly; bent tail (1) , cranioarchschisis (14) , exencephaly (14) , dome shaped head (22) , anophthalmia (15) , brcahynathia (10) and others (19) . Forty five fetuses out of 52 showed soft tissue anomaly; cleft palate (42/52) and anophthalmia (22/52) by high dose of vitamin A. Sixty one fetuses out of 61 (85.2%) showed skull anomaly; defect of frontal, partial and occipital bone (21/61) , defect of palatine bone (52/61) and others (50/61) . In summary, we support that vitamin A is strong teratogen based on our micromass and in vivo data, and olaquindox has a weak teratogenic potential in LB cell but not in CNS cell. We provide the in vivo evidence that a high dose of olaquindox could have weak embryotoxic potential in rats.