Conjugated polyelectrolyte materials for promoting progenitor cell growth without serum

Abstract

The discovery of new active biomaterials for promoting progenitor cell growth and differentiation in serum-free medium is still proving more challenging for the clinical treatments of degenerative diseases. In this work, a conjugated polyelectrolyte, polythiophene derivative (PMNT), was discovered to significantly drive the cell cycle progression from G₁ to S and G₂ phases and thus efficiently promote the cell growth without the need of serum. Furthermore, the fluorescent characteristic of PMNT makes it simultaneously able to trace its cellular uptake and localization by cell imaging. cDNA microarray study shows that PMNT can greatly regulate genes related to cell growth or differentiation. To the best of our knowledge, this is the first example of cell growth or differentiation promotion by polyelectrolyte material without the need of serum, thereby providing an important demonstration of degenerative biomaterial discovery through polymer design.

Figure 1. Chemical structure of PMNT.

Figure 2. Schematic representation of cell growth promotion by PMNT.

Figure 3. Fluorescence images of MC3T3 cells stained with nuclear dye (Hoechst 33258), PMNT, and the overlapped image.

The representative image of PMNT is yellow, the nuclear dye is blue.

Figure 4

(a) Phase contrast images of MC3T3 cells treated with and without PMNT.[PMNT] = 20 μM in repeat unites (RUs). (b) Phase contrast images of MC3T3 cells treated with and without PEI. [PEI] = 2 μM. (c) Cell number as a function of incubation time for MC3T3 cells treated with and without PMNT. [PMNT] = 20 μM in RUs. Error bars correspond to standard deviations from three separate measurements. (d) Cell viability of MC3T3 treated with PMNT using a typical MTT assay. Error bars correspond to standard deviations from three separate measurements.

Figure 5

(a) Typical flow cytometric analysis for cell cycle distribution of MC3T3 cells treated with or without PMNT at 12 h.(b) The proportion of cells in the (S + G2/M) phase as a function of incubation times with PMNT. [PMNT] = 20 μM in RUs.

Figure 6

(a) A typical merged microarray hybridization image of Cy3 (control sample) and Cy5 (PMNT-treated sample).(b) PMNT-regulated changes in gene expression. The Cy3 signal is shown on the x axis and the Cy5 signal is shown on the y axis. The red color stands for the up-regulated genes with the Cy5/Cy3 ratio ≥ 2.0; the green color stands for the down-regulated genes with the Cy5/Cy3 ratio ≤ 0.5; the color black stands for the genes normally expressed. PMNT induces a progressively larger alteration of gene expression.

Figure 7. The relative value of the gene expression level for the PMNT-treated group compared to that of the control group.