Non-contact Coculture Reveals a Comprehensive Response of Chondrocytes Induced by Mesenchymal Stem Cells Through Trophic Secretion

Coculture between mesenchymal stem cells (MSCs) and chondrocytes has significant implications in cartilage regeneration. However, a conclusive understanding remains elusive. Previously, we reported that rabbit bone marrow-derived MSCs (rbBMSCs) could downregulate the differentiated phenotype of rabbit articular chondrocytes (rbACs) in a non-contact coculture system for the first time. In the present study, a systemic investigation was performed to understand the biological characteristics of chondrocytes in coculture with MSCs. Firstly, cells (MSCs and chondrocytes) from different origins were cocultured in transwell system. Different chondrocytes, when cocultured with different MSCs respectively, consistently demonstrated stimulated proliferation, transformed morphology and declined glycosaminoglycan secretion of chondrocytes. Next, cell surface molecules and the global gene expression of rbACs were characterized. It was found that cocultured rbACs showed a distinct surface molecule profile and global gene expression compared to both dedifferentiated rbACs and rbBMSCs. In the end, cocultured rbACs were passaged and induced to undergo the chondrogenic redifferentiation. Better growth and chondrogenesis ability were confirmed compared with control cells without coculture. Together, chondrocytes display comprehensive changes in coculture with MSCs and the cocultured rbACs are beneficial for cartilage repair.

Numerical simulation of chondrocyte growth in 3-D scaffolds / 生物工程学报

Tissue engineering is a promising technique to repair or reconstruct the damaged cartilage in clinical use. However, chondrocyte growth is limited by the mass transport in scaffolds as diffusion is likely to be the primary mechanism. In this study, a mathematical model was developed based on oxygen diffusion and reaction to simulate chondrocyte growth. In order to accord with the fact, effective diffusion coefficients and space limitation were considered in this model and good agreement was found between experimental data and mathematical simulations. Furthermore, relationships established in the model system can be used to optimize the situation in real bioreactors and the design of three-dimensional scaffolds.

Effects of the Culture Method on the Construction of Dermal Substitutes in vitro / 中国生物工程杂志

Culture environment is the key factor in the construction of dermal skin.It was investigated that the effects of the culture methods,including the static culture and spinner flask culture,and stir speeds on the cells proliferation,metabolism and distribution within collagenchitosan sponges.A higher cell density and specific growth rate was obtained with spinner flask culture versus static culture,especially,the 80 r/min spinner flask culture.The cell distribution in dermal substitutes from stirred culture system was more uniform than static culture,as well as that with increase of stir speeds in spinner flask.In summary,the spinner flasks culture with proper stir speed shows promise for the construction of dermal substitutes in vitro.

Gene Expression Analysis of CD34~+ Hematopoietic Stem and Progenitor Cells Grown in Different Culture Environments Using Differential Display / 中国生物工程杂志

Objective: To investigate the changes of gene expression in CD34+ hematopoietic stem and progenitor cells (HSPCs) under different growth environments. Methods: Umbilical cord blood mononuclear cells (UCB MNCs) were cultured in static and stirred systems. After 7 days of culture, CD34+ cells were isolated and total RNA was extracted. Gene expression patterns of CD34+ cells from fresh, static and stirred cultures were compared using differential display (DD). Results: 30 gene fragments displayed differential expression levels based on the conditions of DD. One of differentially expressed genes was identified as RAN, which is a member of oncogene RAS family. This gene may be associated with proliferation of hematopoietic cells. Conclusion: Different growth environments induced differential gene expression patterns of CD34+ HSPCs. These differentially expressed genes would give new insights into optimizing in vitro environments for expanding hematopoietic cells.

Effect of calcium on aggregation and growth of 293 cells / 生物工程学报

The effect of calcium on the aggregation and growth of 293 cells grown in either serum-containing or serum-free medium was investigated in T-flask and spinner bottle, respectively. It was found that the concentration of calcium ion, in the range of 0.1 mmol/L to 1.0 mmol/L, affected adhesion and aggregation of 293 cells severely, but had no distinct effect on growth. The result indicated that the attachment of 293 cells was easier with higher calcium concentration in serum-containing medium. And 293 cells formed aggregates readily in suspension culture. This effect was more profound in cultures with higher calcium concentration. The average diameter( D, mum) of 293 cell aggregates exhibited direct proportion to calcium concentration (c, mmol/L) in serum-free medium. It can be depicted by a simple equation in the range of 0.1 mmol/L to 0.5 mmol/L, i.e. D = 58.65c + 16.96. The aggregation size of 293 cells is regulable in suspension culture, therefore, proper control allows for an easier cell retention, and thus a high cell concentration potentially can be achieved. However, similar growth of 293 cells was observed in cultures with different calcium concentration.

Perfusion culture of hematopoietic cells in a stirred tank bioreactor / 生物工程学报

To optimize the culture environment and protocol of hematopoietic cells' expansion, avoiding the fluctuation caused by medium changing in stirred culture and concentration gradient in static culture, the hematopoietic cells from cord blood (CB) were cultured in a stirred bioreactor connected with a cell retention system, which is a gravity sedimentation settler designed for hematopoietic cell. Total cells expanded 11.5 and 18.6 fold respectively in the twice perfusion stirred cultures, in which CFU-Mix was expanded 23.2 and 20.4 fold, CFU-GM 13.9 fold and 21.5 fold, BFU-E 8.0 fold and 6.9 fold, CD34+ cells 17.1 fold and 15.4 fold. After 12-day culture, it was obtained that 1082 x 10(6) total cells, 6.31 x 10(6) CFU-GM, 6.2 x 10(6) CFU-Mix and 23 x 10(6) CD34+ cells from 267 x 10(6) CB mononuclear cells (MNC) in the first culture, and 1080 x 10(6) total cells, 4.65 x 10(6) CFU-GM, 11.0 x 10(6) CFU-Mix, and 25.0 x 10(6) CD34+ cells from 180 x 10(6) CB MNC. These two cultures met to the clinical scale. Due to the optimized dissolved oxygen (DO) and stable culture environment, the rate of stem/progenitor cells to total cells in the perfusion culture was higher than that in T-flask cell-retention feeding culture. But the cell growth was inhibited in the later phase of perfusion culture, when the cell density is high. The inhibition should be attribute to the high cell density itself. The perfusion culture environment in bioreactor with optimal DO and pH controlling is more favorable for stem/progenitor cells' maintenance and expansion, and the expanded cells' number has reached a clinical scale. But the high cell density in the later phase of perfusion culture caused inhibition to mature hematopoietic cell's growth.

Effects of seeding methods on seeding efficiency and initial cell distribution in 3-D scaffolds / 生物工程学报

Cell seeding of three-dimensional scaffolds is the first step of the cultivation of engineered tissues. The cell seeding density and spatial distribution in a 3-D scaffold are critical to the morphogenetic development of an engineered tissue. In the present work, human fibroblasts were seeded to collagen-chitosan sponges by static seeding, stirred seeding and perfusion seeding. The effects of seeding conditions on the resulting seeding density, the seeding efficiency and the initial cell distribution were studied. The seeding efficiency was relatively high (88.9%) at low inoculation cell density, and decreased rapidly wjth the increasing of inoculation cell density in static seeding. Stirred seeding yielded the lowest seeding efficiency. Nonuniform initial cell distribution was observed in both static and stirred seeding. The perfusion seeding, which has a characteristic of high seeding efficiency (>77%) , high initial cell density and uniform initial cell distribution in 3-D scaffolds, is the optimum method for cell seeding to 3-D scaffold.

Study on the ex vivo expansion characteristics of umbilical cord blood CD34+ cells and mononuclear cells / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the ex vivo expansion characteristics of selected CD(34)(+) cells and mononuclear cells (MNC).</p><p><b>METHODS</b>CD(34)(+) cells were isolated from umbilical cord blood MNC by MiniMACS system, expanded under the same conditions as that for MNC. The effects of re-isolation and the MNC supernatant (MNC-SN) on the selected CD(34)(+) cells were investigated. And the CD(34)(-) cells of MNC were cultured ex vivo.</p><p><b>RESULTS</b>In the culture of selected CD(34)(+) cells, both the colony density and the proportion of the CD(34)(+) cells declined continuously with the culturing, although they presented a high proliferation potential. However, in the culture of the MNC, from day 0 to day 7, the colony density and the proportion of CD(34)(+) cells were increased from 412 +/- 167/10(5) cells and (1.12 +/- 0.42)% to 1 162 +/- 566/10(5) cells and (4.17 +/- 1.44)%, respectively. It was found that both the total cells and the CD(34)(+) cells restored expansion potential by re-isolating. CD(34)(-) cells of MNC had the ability to form colony and could transform to CD(34)(+) cells. MNC-SN can promote colony forming ability and lead to CD(34)(+) cells differentiation at the same time.</p><p><b>CONCLUSIONS</b>In ex vivo culture, selected CD(34)(+) cells presented a high proliferation and differentiation potentials, and the CD(34)(-) cells produced during the cultivation had inhibition effect on CD(34)(+) cells expansion. CD(34)(-) cell population from cord blood MNC contained hematopoietic stem/progenitor cells and the cytokines secreted by CD(34)(-) cells could induce CD(34)(+) cells to more mature colony-forming cells.</p>

Effects of different cooling rates on cryopreservation of hematopoietic stem cells from cord blood / 生物工程学报

Clinical evidence of hematopoietic restoration with umbilical cord blood (UCB) grafts indicates the UCB can be a useful source of hematopoietic stem cells for routine bone marrow reconstitution. Considering (10 +/- 5) x 10(8) nucleared cells per cord blood unit, there is a potential limitation for the use of cord blood in adults, which, however, can be overcome by ex vivo expansion of cells. A prerequisite for expansion is the significantly higher recovery of MNC, CD34+ cells and colony-forming cells (CFC) by thawing cryopreserved MNC. Cooling rate always acts as a critical factor that can affect the recovery of cells. Although the rate of - 1 degrees C/min is adopted in most of the cryopreservations, no data has been reported about the detailed effects of different cooling rates. The aim of the study was to reveal the different effects of cooling rates on cryopreservation of hematopoietic stem cells from cord blood. UCB samples were collected, and cryopreserved as mononuclear cells (MNC) with different cooling rates of - 0.5 degrees C/min, - 1 degrees C/min, - 5 degrees C/min, and the recovery and viability of MNC and CD34+ cells, the clonogenic capacity and the ex vivo expansion potential of UCB progenitor cells were evaluated after thawing. With - 1 degrees C/min cooling rate, the recovery of MNC reached 93.3% +/- 1.8% , viability 95.0% +/- 3.9% , recovery of CD34+ cells 80.0% +/- 17.9% , and clonogenic recovery were 87.1% +/- 5.5%, 88.5% +/- 8.9%, 86.2% +/- 7.4% for BFU-E CFU-GM CFU-MK, respectively. After 14 days of liquid culture, no significant difference was detected in CFC expansion between fresh and cryopreserved MNC cells with - 1 degrees C/min cooling rate, but this was not the case with - 0.5 degreesC/min and - 5 degrees C/min. In conclusion, it was demonstrated that controlling the rate at - 1 degrees C/min is more suitable for cryopreservation of hematopoietic stem cells than - 0.5 degrees C/min and - 5 degrees C/min.

In vitro suspension and bioreactor culture of hematopoietic cells / 生物工程学报

Stirred culture offers a number of advantages over static systems as it maintains a stable, homogeneous culture environment and is easy to scale-up. This paper focused on the development and application of stirred tank bioreactor to culture hematopoietic cells. Preliminary study of stirred culture of hematopoietic cells was carried out in cord blood mononuclear cells culture in spinner flask. The results showed that the amplification rates of total cell, CFU-GM and BFU-E, with the exception of CFU-Mk, were greater in spinner flask than T-flask. The number of total cells increased 20 fold after 14 days incubation in spinner flask. The amplification rates of CFU-GM, CFU-Mk and BFU-E reached maximum at 10th day, 10th day and 7th day respectively, and the maximal amplification rates were 9.2-fold, 5.5-fold and 2.4-fold respectively, whereas the rate of CD34+ cells in spinner flask was (6.7 +/- 4.0)-fold at day 10. These results indicated that the stirred culture system is better than the static culture systems for hematopoietic cell proliferation. The biocompatibility of cord blood MNC to different types of materials used in bioreactors was also tested. The results showed that glass, stainless steel 316L and polytetraflouroethylene (PTFE) supported the growth of hematopoietic cells well. A higher cell density was reached in stirred bioreactors with controlled pH and DO than static culture. These findings suggested that the controlled large-scale culture could be used to overcome the clinical shortage of hematopoietic cells.

Calcium-regulated growth and differentiation of the mouse epidermal keratinocytes / 生物工程学报

The effect of the calcium ion (Ca2+) on the growth and differentiation of the mouse epidermal keratinocytes cultured in serum-free medium was investigated. It was found that the optimal level of calcium ion in the medium was about 0.2 mmol/L. Under such a culture condition the colony forming efficiency, attachment percentage, percentage of the cells with cornified envelops, and percentage of the senesced cells were measured to be about 10.8%, 30.8%, 5.1%, and 26.8%, respectively. However, the Ca2+ concentrations in the medium above 0.6 mmol/L resulted in significant differentiation and senescence of the keratinocytes, which was found to be harmful for keratinocyte growth and expansion in vitro.

The effect of antioxidants on the in vitro life-span of keratinocyte / 生物工程学报

The effect of antioxidants on the in vitro life span of mouse keratinocytes was investigated in this work. It was found that the life span of the keratinocytes cultured in the medium supplemented with antioxidants was extended significantly. The most beneficial antioxidant used in this work was the mercaptoethanol, followed by the catalase and SOD. However, the growth rates of keratinocytes in vitro under all the experimental conditions still declined with the culture time. It was also found that the antioxidants added in the medium were also helpful to enhance the keratinocyte colony formation. In addition, the aging kinetics of the mouse epidermal keratinocytes in vitro were analyzed, and finally the aging rate constants corresponding to antioxidants used were calculated.

Effect of trypsin on the rat keratinocyte separation and subculture / 生物工程学报

The effect of trypsin on the separation an subculture of the keratinocytes was investigated in this work. It was found that when 0.25% trypsin was employed for 5 minutes to separate keratinocytes, the number of active keratinocytes and the cells capable of forming colony were higher than those of other experimental conditions. The maximum attached ratio of primary keratinocytes was obtained when skin tissues were treated at 0.05% concentration of trypsin. With the increase of the trypsin concentrations, the attached ratio, attachment rate constant, and colony forming efficiency were all increased. Thus, 0.25% concentration of trypsin was recommended for separating and subculturing the keratinocytes.

In vitro culture of umbilical cord blood MNC and CD34+ selected cells / 生物工程学报

For in vitro studies, both CD34+ selected cell and mononuclear cell (MNC) can be used to expand hematopoietic stem/progenitor cells. To investigate the expansion characteristics of mononuclear cells (MNC) and CD34+ selected cells the two cell fractions were cultured in the medium containing cytokine cocktails of SCF + IL-3 + IL-6 + FL + Tpo. It was found that the CD34+ selected cells had presented a high proliferation potential. The expansion of CD34+ selected cells could be maintained for 8 weeks while that of MNCs declined after 4 weeks. During the culture period, the maximum expansion of total cells in CD34+ selected cell culture achieved 31,270.9 +/- 8640.5 times, while that of MNC reached 50.9 +/- 8.2 times only. In the culture of MNCs, the colony density and the proportion of CD34+ cells increased from day 0 to day 7. However, in the culture of CD34+ selected cells, both the colony density and the proportion of CD34+ cells declined continuously during the whole culture period. During the ex vivo culture of CD34+ selected cells, the maximum expansion of CFU-GM and CD34+ cells achieved 185.7 +/- 14.1 fold and 191.7 +/- 188.8 fold, respectively. They are much higher than that of MNC, which were 12.4 +/- 3.2 fold and 50.6 +/- 33.2 fold only. While the BFU-E of both cell fractions only expanded by few times, which were 7.2 +/- 5.2 and 10.1 +/- 3.4 times, respectively. The results showed that the CD34+ selected cells culture could obtain more CFU-GM cells and CD34+ cells during the whole culture period.