Coherent anti-Stokes Raman scattering microscopy of human smooth muscle cells in bioengineered tissue scaffolds

The integration of living, human smooth muscle cells in biosynthesized cellulose scaffolds was monitored by nonlinear microscopy toward contractile artificial blood vessels. Combined coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) microscopy was applied for studies of the cell interaction with the biopolymer network. CARS microscopy probing CH(2)-groups at 2845 cm(-1) permitted three-dimensional imaging of the cells with high contrast for lipid-rich intracellular structures. SHG microscopy visualized the fibers of the cellulose scaffold, together with a small signal obtained from the cytoplasmic myosin of the muscle cells. From the overlay images we conclude a close interaction between cells and cellulose fibers. We followed the cell migration into the three-dimensional structure, illustrating that while the cells submerge into the scaffold they extrude filopodia on top of the surface. A comparison between compact and porous scaffolds reveals a migration depth of <10 μm for the former, whereas the porous type shows cells further submerged into the cellulose. Thus, the scaffold architecture determines the degree of cell integration. We conclude that the unique ability of nonlinear microscopy to visualize the three-dimensional composition of living, soft matter makes it an ideal instrument within tissue engineering

Conditioned media from human macrophages of M1 phenotype attenuate the cytotoxic effect of 5‑fluorouracil on the HT‑29 colon cancer cell line

Resistance of tumor cells to chemotherapy, such as 5‑fluorouracil (5‑FU), is an obstacle for successful treatment of cancer. As a follow‑up of a previous study we have investigated the effect of conditioned media (CM) from macrophages of M1 or M2 phenotypes on 5‑FU cytotoxicity on the colon cancer cell lines HT‑29 and CACO‑2. HT‑29 cells, but not CACO‑2 cells, having been treated with a combination of M1 CM and 5‑FU recovered their cell growth to a much larger extent compared to cells having been treated with 5‑FU alone when further cultured for 7 days in fresh media. M1 CM treatment of HT‑29, but not CACO‑2 cells, induced cell cycle arrest in the G0/G1 and G2/M phases. 5‑FU treatment induced accumulation of cells in S‑phase in both HT‑29 and CACO‑2 cells. This accumulation of cells in S‑phase was attenuated by combined M1 CM and 5‑FU treatment in HT‑29 cells, but not in CACO‑2 cells. The mRNA expression of cell cycle regulatory proteins and 5‑FU metabolic enzymes were analyzed in an attempt to find possible mechanisms for the M1 CM induced attenuation of 5‑FU cytotoxicity in HT‑29. Thymidylate synthetase (TS) and thymidine phosphorylase (TP) were found to be substantially downregulated and upregulated, respectively, in HT‑29 cells treated with M1 CM, making them unlikely as mediators of reduced 5‑FU cytotoxicity. Among cell cycle regulating proteins, p21 was induced in HT‑29 cells, but not in CACO‑2 cells, in response to M1 CM treatment. However, small interfering RNA (siRNA) knockdown of p21 had no effect on the M1 CM induced cell cycle arrest seen in HT‑29 and neither did it change the growth recovery after combined treatment of HT‑29 cells with M1 CM and 5‑FU. In conclusion, treatment of HT‑29 cells with M1 CM reduces the cytotoxic effect of 5‑FU and this is mediated by a M1 CM induced cell cycle arrest in the G0/G1 and G2/M phases. So far, we lack an explanation why this action is absent in the CACO‑2 cells. The current findings may be important for optimization of chemotherapy in colon cancer

Conditioned media from macrophages of M1, but not M2 phenotype, inhibit the proliferation of the colon cancer cell lines HT-29 and CACO-2

Solid tumors are infiltrated by stroma cells including macrophages and these cells can affect tumor growth, metastasis and angiogenesis. We have investigated the effects of conditioned media (CM) from different macrophages on the proliferation of the colon cancer cell lines HT-29 and CACO-2. CM from THP-1 macrophages and monocyte-derived human macrophages of the M1 phenotype, but not the M2 phenotype, inhibited proliferation of the tumor cells in a dose-dependent manner. Lipopolysaccaharide and interferon γ was used for differentiation of macrophages towards the M1 phenotype and CM were generated both during differentiation (M1DIFF) and after differentiation (M1). M1 and M1DIFF CM as well as THP-1 macrophage CM resulted in cell cycle arrest in HT-29 cells with a decrease of cells in S phase and an increase in G2/M phase. Treatment of HT-29 cells with M1DIFF, but not M1 or THP-1 macrophage CM, resulted in apoptosis of about 20% of the tumor cells and this was accompanied by lack of recovery of cell growth after removal of CM and subsequent culture in fresh media. A protein array was used to identify cytokines released from M1 and M2 macrophages. Among the cytokines released by M1 macrophages, tumor necrosis factor α and CXCL9 were tested by direct addition to HT-29 cells, but neither affected proliferation. Our results indicate that M1 macrophages inhibit colon cancer cell growth and have the potential of contributing to reducing tumor growth in vivo

Effect of macrophages on breast cancer cell proliferation, and on expression of hormone receptors, uPAR and HER-2

Malignant tumors, including breast cancers, are frequently infiltrated with innate immune cells and tumor-associated macrophages (TAMs) represent the major inflammatory component in stroma of many tumors. In this study, we examined the immunoreactivity of the macrophage markers CD68 and CD163 as well as the hormone receptors estrogen receptor alpha (ER alpha), progesterone receptor (PR), estrogen receptor beta 1 (ER beta 1), human epidermal growth factor receptor 2 (HER-2), matrix metalloproteinase 9 (MMP-9), urokinase-type plasminogen activator receptor (uPAR) and the proliferations marker Ki67 in 17 breast cancer biopsies. The quantitative score for CD68(+) and CD163(+) strongly indicate M2 phenotype dominance in the currently investigated biopsies. We found that an increasing level of macrophages was negatively associated with ER alpha or PR, whereas a positive association was observed for Ki-67 or uPAR. No significant association could be seen between the level of macrophage and HER-2, ER beta 1 or MMP-9 expression. Effect of conditioned media (CM) generated from cultured human M1 and M2 macrophage phenotypes were investigated on the proliferation and expression of selected markers in the T47D breast cancer cell line. We found that in contrast to the in vivo situation, in particularly the CM from M1 macrophages decreased the growth and Ki67 expression in T47D, and significantly increased ER beta 1 mRNA levels. Moreover, in accordance to the in vivo situation the CM from the macrophages decreased the expression of ER alpha protein as well as ER alpha or PR mRNA. In conclusion our results show that macrophages alone have the capability to decrease the tumor cell expression of ER alpha and PR in vitro. In the tumor environment in vivo macrophages also contribute to an increase in tumor cell expression of uPAR and Ki67, suggesting that macrophages are involved in impairing the prognosis for breast cancer patients

Intravital fluorescent microscopic evaluation of bacterial cellulose as scaffold for vascular grafts.

Although commonly used synthetic vascular grafts perform satisfactorily in large caliber blood vessels, they are prone to thrombosis in small diameter vessels. Therefore, small vessels might benefit from tissue engineered vascular grafts. This study evaluated bacterial cellulose (BC) as a potential biomaterial for biosynthetic blood vessels. We implanted the dorsal skinfold chambers in three groups of Syrian golden hamsters with BC (experimental group), polyglycolic acid, or expanded polytetrafluorethylene (control groups). Following implantation, we used intravital fluorescence microscopy, histology, and immunohistochemistry to analyze the biocompatibility, neovascularization, and incorporation of each material over a time period of 2 weeks. Biocompatibility was good in all groups, as indicated by the absence of leukocyte activation upon implantation. All groups displayed angiogenic response in the host tissue, but that response was highest in the polyglycolic acid group. Histology revealed vascularized granulation tissue surrounding all three biomaterials, with many proliferating cells and a lack of apoptotic cell death 2 weeks after implantation. In conclusion, BC offers good biocompatibility and material incorporation compared with commonly used materials in vascular surgery. Thus, BC represents a promising new biomaterial for tissue engineering of vascular grafts

Intravital fluorescent microscopic evaluation of bacterial cellulose as scaffold for vascular grafts.

Although commonly used synthetic vascular grafts perform satisfactorily in large caliber blood vessels, they are prone to thrombosis in small diameter vessels. Therefore, small vessels might benefit from tissue engineered vascular grafts. This study evaluated bacterial cellulose (BC) as a potential biomaterial for biosynthetic blood vessels. We implanted the dorsal skinfold chambers in three groups of Syrian golden hamsters with BC (experimental group), polyglycolic acid, or expanded polytetrafluorethylene (control groups). Following implantation, we used intravital fluorescence microscopy, histology, and immunohistochemistry to analyze the biocompatibility, neovascularization, and incorporation of each material over a time period of 2 weeks. Biocompatibility was good in all groups, as indicated by the absence of leukocyte activation upon implantation. All groups displayed angiogenic response in the host tissue, but that response was highest in the polyglycolic acid group. Histology revealed vascularized granulation tissue surrounding all three biomaterials, with many proliferating cells and a lack of apoptotic cell death 2 weeks after implantation. In conclusion, BC offers good biocompatibility and material incorporation compared with commonly used materials in vascular surgery. Thus, BC represents a promising new biomaterial for tissue engineering of vascular grafts