Elevated monocytes in patients with critical limb ischemia diminish after bypass surgery.
BACKGROUND
Mononuclear cells (MNC) increase neovascularization and ulcer healing after injection into an ischemic extremity. Circulating MNC are composed of lymphocytes (85%), monocytes (15%), and endothelial progenitor cells (EPC; 0.03%). We hypothesized that ischemic limbs secrete paracrine signals to recruit bone marrow-derived monocytes and EPC into the circulation, such that patients with critical limb ischemia (CLI) have increased circulating monocytes compared with control patients. We also hypothesized that circulating monocytes and EPC recruitment decrease after resolution of ischemia with successful revascularization.


METHODS
We reviewed the records of all patients at the VA Connecticut Healthcare System undergoing primary, functionally successful, lower extremity peripheral bypass surgery between 2002 and 2007, but only including patients with both preoperative and postoperative (>4 mo) complete blood counts with differentials.


RESULTS
Patients with CLI (n = 24) had elevated preoperative monocyte counts compared with control patients (n = 8) (0.753 ± 0.04 versus 0.516 ± 0.05; P = 0.0046), whereas the preoperative lymphocyte counts were not significantly different. After revascularization, ischemic patients had decreased monocyte counts compared with control patients (-20% versus + 55%; P = 0.0003), although lymphocyte counts were unchanged in both groups. Diabetic patients also had reduced postoperative monocyte counts (-32% versus + 13%; P = 0.035). Multivariable logistic regression demonstrated that the only factor that independently predicted reduced postoperative monocyte count was preoperative CLI (P = 0.038).


CONCLUSIONS
Patients with CLI have increased numbers of circulating monocytes, and the monocyte number decreases with resolution of ischemia after successful revascularization. Circulating monocytes may be a clinically useful perioperative marker in patients with CLI undergoing vascular surgery.
Department of Surgery, VA Connecticut Healthcare System, West Haven, Connecticut, USA.
Dania
D
Magri
Penny
P
Vasilas
Akihito
A
Muto
Tamara N
TN
Fitzgerald
Tiffany T
TT
Fancher
Aaron J
AJ
Feinstein
Toshiya
T
Nishibe
Alan
A
Dardik
D000368:Aged; D016022:Case-Control Studies; D002452:Cell Count; D004730:Endothelium, Vascular / Q000473:pathology; D006801:Humans; D007866:Leg / Q000098:blood supply*; D016015:Logistic Models; D008297:Male; D009000:Monocytes / Q000473:pathology*; D017063:Outcome Assessment, Health Care; D012039:Regional Blood Flow; D015427:Reperfusion Injury / Q000473:pathology* / Q000601:surgery*; D012189:Retrospective Studies; D013234:Stem Cells / Q000473:pathology; D058017:Vascular Grafting