This study was a time activity pattern assessment focused on transportation in subpopulation groups using the ‘Time-Use Survey’ conducted by the National Statistical Office in Korea in 2009. The time activity patterns of transportation on weekdays were analyzed, looking at average travel time in Seoul, Gyeonggido and the whole country. Various subpopulation groups were classified such as students, the elderly, workers and housewives. The population of Gyeonggido had a higher average transportation time than that of Seoul. Workers showed the highest weekly average travel, while the students group showed the lowest tendency. The times spent in walking, bus, subway and taxi were the highest in areas other than Gyeonggido, where the use of private vehicles such as car was higher. Therefore, exposure to hazardous air pollutants may vary depending on the transportation method and time spent. This results indicate that time activity pattern assessment on transportation may be an important element of exposure assessment.

Multipotent perivascular stem cells (PVCs) have gained much attention as an alternative source for cell based regenerative medicine in recent years. Due to their rarity in human tissues, developing methods to efficiently isolate and expand PVCs from various fetal and adult tissues is necessary to obtain a clinically relevant number of cells that maintain progenitor potency. Here, we report on a non-enzymatic isolation (NE) method of PVCs from human umbilical cords (HUCs) and compare its efficiency with the conventional collagenase treatment method (CT) in terms of proliferation and immunophenotypes. The cells isolated by NE displyed acceptable surface marker profile of PVCs and showed multilineage (osteogenic, chondrogenic, and adipogenic) differentiation potential. While both methods provided similar levels or patterns of proliferation and immunophenotypes, PVCs by NE retained a higher level of CD146(+) frequency compared to that of CT over passage. Furthermore, we have investigated potentials of various exogenous factors to promote proliferation of HUCPVCs in vitro. Among these factors, supplementation of basic fibroblast growth factor (bFGF) provided the optimal condition to significantly enhance the proliferation rate of HUCPVC and increased a proportion of stage-specific antigen-4 (SSEA-4) positive subset. Collectively, our study suggests that NE method with bFGF supplementation offers an alternative way to obtain sufficient numbers of HUCPVCs with higher number of primitive SSEA-4(+) subpopulation that are applicable in therapeutic doses for regenerative medicine.