ABSTRACT
<p><b>BACKGROUND</b>The proliferation and apoptosis property of mesenchymal stem cells derived from peripheral blood (PB-MSCs) were investigated under hypoxia and serum deprivation conditions in vitro so as to evaluate the feasibility for autologous PB-MSCs applications in cartilage repair.</p><p><b>METHODS</b>MSCs were mobilized into peripheral blood by granulocyte colony stimulating factor (G-CSF) and AMD3100. The blood samples were collected from central ear artery of rabbits. Adhered cells were obtained by erythrocyte lysis buffer and identified as MSCs by adherence to plastic, spindle shaped morphology, specific surface markers, differentiation abilities into osteoblasts, adipocytes and chondroblasts in vitro under appropriate conditions. MSCs were cultured in four groups at different oxygen tension (20% O2 and 2% O2), with or without 10% fetal bovine serum (FBS) conditions: 20% O2 and 10% FBS complete medium (normal medium, N), 20% O2 and serum deprivation medium (D), 2% O2 and 10% FBS complete medium (hypoxia, H), 2% O2 and serum deprivation (HD). Cell proliferation was determined by CCK-8 assay. Apoptosis was detected by Annexin V/PI and terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL) staining.</p><p><b>RESULTS</b>Spindle-shaped adherent cells were effectively mobilized from peripheral blood by a combined administration of G-CSF plus AMD3100. These cells showed typical fibroblast-like phenotype similar to MSCs from bone marrow (BM-MSCs), and expressed a high level of typical MSCs markers CD29 and CD44, but lacked in the expression of hematopoietic markers CD45 and major histocompatibility complex Class II (MHC II). They could also differentiate into osteoblasts, adipocytes and chondroblasts in vitro under appropriate conditions. No significant morphological differences were found among the four groups. It was found that hypoxia could enhance proliferation of PB-MSCs regardless of serum concentration, but serum deprivation inhibited proliferation at the later stage of culture. Apart from that, hypoxia or serum deprivation could promote the apoptosis of PB-MSCs after 48 hours; the effect was stronger when these two conditions combined together. Furthermore, the effect of serum deprivation on apoptosis was stronger compared with that of hypoxia.</p><p><b>CONCLUSIONS</b>PB-MSCs possess similar phenotypes as BM-MSCs. Their differentiation and proliferation abilities make them a new source of seed cells for ischemia-related cell therapy and tissue engineering in the field of the articular cartilage repair.</p>
Subject(s)
Animals , Rabbits , Apoptosis , Physiology , Cell Hypoxia , Physiology , Cell Proliferation , Cells, Cultured , In Situ Nick-End Labeling , Mesenchymal Stem Cells , Cell BiologyABSTRACT
<p><b>BACKGROUND</b>Several reports have shown the progression of articular cartilage degeneration after anterior cruciate ligament (ACL) reconstruction. No report has been published about the cartilage comparing changes after single-bundle (SB) and double-bundle (DB) ACL reconstructions. The purpose of this study was to evaluate the articular cartilage changes after SB and DB ACL reconstructions by second-look arthroscopy.</p><p><b>METHODS</b>Ninety-nine patients who received arthroscopic ACL reconstruction were retrospectively reviewed at an average of 14 months after reconstruction, 58 patients underwent SB ACL reconstruction and 41 patients underwent DB ACL reconstruction. Hamstring tendon autografts were used in all patients. Second-look arthroscopy was done in conjunction with the tibial staple fixation removal at least one year after the initial ACL reconstruction. Arthroscopic evaluation and grading of the articular cartilage degeneration for all patients were performed at the initial ACL reconstruction, and at the second-look arthroscopy.</p><p><b>RESULTS</b>The average cartilage degeneration at the patellofemoral joint (PFJ) was found significantly worsened after both SB and DB ACL reconstructions. This worsening were not seen at medial tibiofemoral joint (TFJ) and lateral TFJ. Grade II cartilage damage was the most common. At second-look arthroscopy, the average patellar cartilage degeneration was 1.14 ± 0.14 (at first look 0.52 ± 0.11) for the SB group, and 1.22 ± 0.15 (at first look 0.56 ± 0.12) for the DB group. The average trochlear cartilage degeneration was 1.05 ± 0.16 (at fist look 0.10 ± 0.06) and 0.66 ± 0.17 (at fist look 0.17 ± 0.09), respectively. The average patellar cartilage degeneration showed no significant difference in both groups. However, the average trochlea cartilage degeneration in DB group was significantly less than in SB group.</p><p><b>CONCLUSIONS</b>Patellofemoral cartilage degeneration continued to aggravate after ACL reconstruction. DB ACL reconstruction could significantly decrease the trochlea cartilage degeneration compared with SB ACL reconstruction.</p>