The murine skeletal muscle contains hematopoietic stem cells, but this potential has so far not been studied quantitatively or qualitatively in vitro. To quantify the hematopoietic stem cell potential, we have used hi...The murine skeletal muscle contains hematopoietic stem cells, but this potential has so far not been studied quantitatively or qualitatively in vitro. To quantify the hematopoietic stem cell potential, we have used highly purified SP/CD45^＋ cells in long-term culture initiating cell （LTC-IC） assays. The SP/CD45^＋ cell population purified from murine muscle was found to have significant stem cell activity with an LTC-IC frequency of 1/640. Single-cell-sorted SP/CD45^＋ cells from muscle exhibited robust proliferative activity in vitro at day 16 （380-fold amplification）, especially after culture with OP-9 layers that also support embryonic stem cells. Amplified cell populations originating from single cells exhibited multilineage differentiation ability with evidence of myeloid, lymphoid and NK cell markers. Thus, our results demonstrate that hematopoietic stem cells that can be quantified by LTC-IC assays exist in the murine skeletal muscle and show also for the first time, at the single-cell level, that these cells exhibit multilineage differentiation ability and major proliferative potential.展开更多
OBJECTIVE: To investigate the reasons for the rarity of metastases in skeletal muscle. METHODS: By injecting tumor cells (Walker256 rat carcinosarcoma) through the iliac artery (experimental group) and the tail vein (...OBJECTIVE: To investigate the reasons for the rarity of metastases in skeletal muscle. METHODS: By injecting tumor cells (Walker256 rat carcinosarcoma) through the iliac artery (experimental group) and the tail vein (control group), animal models of blood-borne metastases were established. The quadriceps femoris muscle and lungs were observed grossly and microscopically. Immunohistochemistry was applied to investigate the expression of vascular cell adhesion molecule-1 (VCAM-1) in the microvascular endothelium of these organs. Primary culture of rat skeletal muscle cells was established and conditioned medium (MCM) was collected. Effects of MCM on several tumor cell lines and the biochemical characteristics of skeletal muscle delivered tumor factor(s) were tested by MTT assay. Apoptosis and morphological examination were carried out to investigate the antitumor mechanisms of MCM. RESULTS: In the experimental group, there were no definite metastases observed in muscle cells. In the control group, lung metastases were present in the lungs of all rats that were sacrificed at the 14th day or died spontaneously (17 rats in all). There was no significant difference between the increase in VCAM-1 in quadriceps femoris muscle 7 days after iliac artery injection and that in lungs 7 days after tail vein injection (P > 0.05). In vitro studies showed that the proliferation of tumor cell lines of mouse SP2/0 myeloma, rat Walker256 carcinosarcoma or human chronic granulocytic leukemia K562, human acute lymphatic leukemia HL-60, LS-174-T colon adenocarcinoma, PC3-M prostatic carcinoma and lung giant cell carcinoma with different metastatic potency (PLA801-C with low metastatic potency, PLA801-D with high metastatic potency) was significantly inhibited when cultured with MCM (P展开更多
文摘The murine skeletal muscle contains hematopoietic stem cells, but this potential has so far not been studied quantitatively or qualitatively in vitro. To quantify the hematopoietic stem cell potential, we have used highly purified SP/CD45^＋ cells in long-term culture initiating cell （LTC-IC） assays. The SP/CD45^＋ cell population purified from murine muscle was found to have significant stem cell activity with an LTC-IC frequency of 1/640. Single-cell-sorted SP/CD45^＋ cells from muscle exhibited robust proliferative activity in vitro at day 16 （380-fold amplification）, especially after culture with OP-9 layers that also support embryonic stem cells. Amplified cell populations originating from single cells exhibited multilineage differentiation ability with evidence of myeloid, lymphoid and NK cell markers. Thus, our results demonstrate that hematopoietic stem cells that can be quantified by LTC-IC assays exist in the murine skeletal muscle and show also for the first time, at the single-cell level, that these cells exhibit multilineage differentiation ability and major proliferative potential.
文摘OBJECTIVE: To investigate the reasons for the rarity of metastases in skeletal muscle. METHODS: By injecting tumor cells (Walker256 rat carcinosarcoma) through the iliac artery (experimental group) and the tail vein (control group), animal models of blood-borne metastases were established. The quadriceps femoris muscle and lungs were observed grossly and microscopically. Immunohistochemistry was applied to investigate the expression of vascular cell adhesion molecule-1 (VCAM-1) in the microvascular endothelium of these organs. Primary culture of rat skeletal muscle cells was established and conditioned medium (MCM) was collected. Effects of MCM on several tumor cell lines and the biochemical characteristics of skeletal muscle delivered tumor factor(s) were tested by MTT assay. Apoptosis and morphological examination were carried out to investigate the antitumor mechanisms of MCM. RESULTS: In the experimental group, there were no definite metastases observed in muscle cells. In the control group, lung metastases were present in the lungs of all rats that were sacrificed at the 14th day or died spontaneously (17 rats in all). There was no significant difference between the increase in VCAM-1 in quadriceps femoris muscle 7 days after iliac artery injection and that in lungs 7 days after tail vein injection (P > 0.05). In vitro studies showed that the proliferation of tumor cell lines of mouse SP2/0 myeloma, rat Walker256 carcinosarcoma or human chronic granulocytic leukemia K562, human acute lymphatic leukemia HL-60, LS-174-T colon adenocarcinoma, PC3-M prostatic carcinoma and lung giant cell carcinoma with different metastatic potency (PLA801-C with low metastatic potency, PLA801-D with high metastatic potency) was significantly inhibited when cultured with MCM (P
