Huang Ying, Chen Bing, Zhang Jian
Department of Vascular Surgery, Xuanwu Hospital, Capital Medical University, Beijing, China (mainland).
Med Sci Monit. 2014 Nov 5;20:2171-6. doi: 10.12659/MSM.892354.
Bone marrow stromal cells (BMSCs) play an important role in ischemic limb angiogenesis. BMSCs cultured in vitro can be exposed to oxygen tension much higher than that experienced in vivo. This study assessed oxygen tension in bone marrow and ischemic muscle in vivo, and then identified an appropriate oxygen concentration for culturing BMSCs.
MATERIAL/METHODS: Unilateral hind limb ischemia was surgically induced in 30 mice, and tissue oxygen tension in bilateral gastrocnemius muscles and femoral bone marrow was monitored in vivo using a micro-electrode at 24 hours, 1 week, 2 weeks, and 3 weeks after modeling. Media used for culturing normal marrow, muscle, and artery tissue were incubated with various oxygen concentrations, and O2 tension was continuously monitored. Oxygen tension in aortic arterial blood was monitored using a micro-electrode and blood gas analyzer, and the results were compared.
Oxygen tension in ischemic gastrocnemius muscle reached a nadir at 1 week after ischemic modeling, when histological changes were most noticeable. Culture media incubated with 3%, 6%, and 14% oxygen (the normal oxygen levels of bone marrow, muscle, and arterial blood, respectively) required 9, 6, and 2 hours, respectively, to reach an equilibrated oxygen tension, and oxygen tension was elevated by 1.6-, 1.2-, and 0.4-fold, respectively, upon re-exposure of the media to air.
Physiological oxygen tension differs in different tissues. A 3% O2 concentration mimics the physiological O2 exposure experienced by BMSCs and represents the hypoxic concentration. Culture medium incubated under hypoxic conditions requires a prolonged period of time to regain equilibrated oxygen tension.
骨髓基质细胞（BMSCs）在缺血肢体血管生成中起重要作用。体外培养的BMSCs可暴露于远高于体内的氧张力环境。本研究评估了体内骨髓和缺血肌肉中的氧张力，然后确定了培养BMSCs的合适氧浓度。
材料/方法：对30只小鼠进行手术诱导单侧后肢缺血，并在建模后24小时、1周、2周和3周时，使用微电极在体内监测双侧腓肠肌和股骨骨髓中的组织氧张力。将用于培养正常骨髓、肌肉和动脉组织的培养基在不同氧浓度下孵育，并持续监测氧张力。使用微电极和血气分析仪监测主动脉动脉血中的氧张力，并比较结果。
缺血建模后1周，缺血腓肠肌中的氧张力降至最低点，此时组织学变化最为明显。分别用3%、6%和14%氧气（分别为骨髓、肌肉和动脉血的正常氧水平）孵育的培养基，分别需要9小时、6小时和2小时达到平衡氧张力，并且当培养基再次暴露于空气中时，氧张力分别升高了1.6倍、1.2倍和0.4倍。
不同组织中的生理氧张力不同。3%的氧浓度模拟了BMSCs所经历的生理氧暴露，代表缺氧浓度。在缺氧条件下孵育的培养基需要较长时间才能恢复平衡氧张力。
