Comprehension of attachment and multiplication properties by observing individual cell behaviors in anchorage-dependent culture

An in silico prediction tool for the expansion culture of human skeletal muscle myoblasts

Regenerative therapy using autologous skeletal myoblasts requires a large number of cells to be prepared for high-level secretion of cytokines and chemokines to induce good regeneration of damaged regions. However, myoblast expansion culture is hindered by a reduction in growth rate owing to cellular quiescence and differentiation, therefore optimization is required. We have developed a kinetic computational model describing skeletal myoblast proliferation and differentiation, which can be used as a prediction tool for the expansion process. In the model, myoblasts migrate, divide, quiesce and differentiate as observed during in vitro culture. We assumed cell differentiation initiates following cell-cell attachment for a defined time period. The model parameter values were estimated by fitting to several predetermined experimental datasets. Using an additional experimental dataset, we confirmed validity of the developed model. We then executed simulations using the developed model under several culture conditions and quantitatively predicted that non-uniform cell seeding had adverse effects on the expansion culture, mainly by reducing the existing ratio of proliferative cells. The proposed model is expected to be useful for predicting myoblast behaviours and in designing efficient expansion culture conditions for these cells.

Experimental analysis and modelling of in vitro HUVECs proliferation in the presence of various types of drugs

OBJECTIVES

This study focuses on experimental analysis and corresponding mathematical simulation of in vitro HUVECs (human umbilical vein endothelial cells) proliferation in the presence of various types of drugs.

MATERIALS AND METHODS

HUVECs, once seeded in Petri dishes, were expanded to confluence. Temporal profiles of total count obtained by classic haemocytometry and cell size distribution measured using an electronic Coulter counter, are quantitatively simulated by a suitable model based on the population balance approach. Influence of drugs on cell proliferation is also properly simulated by accounting for suitable kinetic equations.

RESULTS AND DISCUSSION

The models' parameters have been determined by comparison with experimental data related to cell population expansion and cell size distribution in the absence of drugs. Inhibition constant for each type of drug has been estimated by comparing the experimental data with model results concerning temporal profiles of total cell count. The reliability of the model and its predictive capability have been tested by simulating cell size distribution for experiments performed in the presence of drugs. The proposed model will be useful in interpreting effects of selected drugs on expansion of readily available human cells.

Automating the expansion process of human skeletal muscle myoblasts with suppression of myotube formation

An intelligent culture system accompanied by automated operations (liquid transfer and cell passage) was newly developed to perform serial cultures of human skeletal muscle myoblasts. To realize a desired performance, a laminin-coated surface was applied to myoblast expansion in a culture flask. It was found that the laminin coating enhanced the overall growth ability attributable not to shortening of the doubling time but to prevention of differentiation toward myotube formation, compared with that on a conventional plain surface. In addition, the effects of seeding density and confluence degree on the growth were investigated quantitatively in terms of cell attachment and division as well as proliferative cell population in the culture on the laminin-coated surface. With increasing in seeding density, the number of proliferative cells decreased at the end of culture accompanied by an increase in the confluence degree, which caused poor attachment of the passaged cells on the surface in the subsequent culture. The quantitative analyses of these cell behaviors helped us determine the appropriate seeding density and attainable confluence degree during one passage, which were 1.0 x 10(3) cells/cm(2) and 0.5 as the initial and boundary conditions, respectively. An automated culture system that could manage two serial cultures by monitoring the confluence degree was constructed. The automated operation with the intelligent determination of the time for passage was successfully performed without serious loss of growth activity, compared with manual operation using conventional flasks. These results indicated that the monitoring of confluence degree is effective to perform the culture passage of myoblasts, being contributable to automating the cell expansion process.

Experimental analysis and modelling of in vitro proliferation of mesenchymal stem cells

OBJECTIVES

Stem cell therapies based on differentiation of adult or embryonic stem cells into specialized ones appear to be effective for treating several human diseases. This work addresses the mathematical simulation of proliferation kinetics of stem cells.

MATERIALS AND METHODS

Sheep bone marrow mesenchymal stem cells (phenotype characterized by flow cytometry analysis) seeded at different initial concentrations in Petri dishes were expanded to confluence. Sigmoid temporal profiles of total counts obtained through classic haemocytometry were quantitatively interpreted by both a phenomenological logistic equation and a novel model based on a one-dimensional, single-staged population balance approach capable of taking into account contact inhibition at confluence. The models' parameters were determined by comparison with experimental data on population expansion starting from single seeding concentration. Reliability of the models was tested by predicting cell proliferation carried out starting from different seeding concentrations.

RESULTS AND DISCUSSION

It was found that the proposed population balance modelling approach was successful in predicting the experimental data over the whole range of initial cell numbers investigated, while prediction capability of phenomenological logistic equation was more limited.