An approach for promoting the adherence of chondrogenic progenitor cells to specific matrix molecules has been tested in a cartilage defect model. Culture-expanded pre-chondrocytes fluorescently labeled with a vital dye were coated by a two-step method wherein lipidated protein G was first allowed to intercalate into cell membranes, and a second incubation in a solution of antibodies to cartilage matrix antigens allowed the binding of the antibodies to the protein G, on the external surface of the cell. The coating technique (termed "cell painting") does not effect cell viability or inhibit growth and chondrogenic potential. Painted cells were then added to rabbit cartilage explants that had a partial-thickness defect, washed, and prepared for histological examination and for confocal microscopy. The histological observations and the confocal observations and fluorescent intensity quantification consistently demonstrated that progenitor cells painted with multiple antibodies were capable of preferential binding to the exposed cartilage matrix within the defect. These results demonstrate that painting cell membranes with antibodies to matrix molecules is an effective method for promoting the adherence of stem or progenitor cells to a cartilage injury site.

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Coronary artery bypass grafting (CABG) is one of the most frequently performed operations in the United States. The use of internal mammary artery (IMA) grafting has been identified as increasing the risk of sternal wound infections and mediastinitis. The purpose of our study was to prospectively evaluate the effect of different techniques of left internal mammary artery (LIMA) harvesting on sternal vascularity. Thirty-three patients undergoing primary coronary artery bypass grafting were studied. The patients were divided into groups that received a skeletonized IMA (group I, n=11), a pedicled IMA (group II, n=12), or a semiskeletonized IMA (group III, n=10) graft. Each patient underwent a preoperative 99mTc-methylene diphosphonate bone scan using single photon emission computed tomography (SPECT). The ratio of the mean counts/pixel for each side of the sternum was obtained. Post-operatively, all patients had a repeat bone SPECT. Ratios of unilateral sternal uptakes were compared to the preoperative study. A univariable analysis of post-operative to pre-operative ratios revealed statistically significant reduction in vascularity to the left side of the sternum post-operatively in group II compared with groups I and III (0.68 0.12 vs 0.99 0.24 and 0.93 0.09; P<0.01). There was no difference between groups I and III (P=1). Multivariable analysis revealed only the type of harvesting to be associated with post-operative reduction in left to right sternal activity ratio (P<0.02). Pairwise comparisons revealed that differences are due to pedicled type of harvesting (group II vs group I, P=0.03; II vs III, P=0.001; and I vs III, P=0.115). A pedicled IMA graft causes acute post-operative sternal ischaemia. This does not occur when the IMA is skeletonized or semiskeletonized. Hence, it may be prudent to minimize dissection during mobilization of the IMA to decrease the likelihood of post-operative sternal complications.