Local Delivery of Platelets with Encapsulated lloprost to Balloon Injured Pig Carotid Arteries: Effect on Platelet Deposition and Neointima Formation

Summary

Local delivery of a drug to the arterial wall during angioplasty is an approach which might reduce the incidence of occlusive events such as thrombosis and restenosis, without the risk of systemic side effects. By exploiting their natural primary haemostatic properties, platelets, with encapsulated drugs, can be targeted to a vessel wall injury site and act as a depot for sustained release. The platelet plasma membrane can be reversibly permeabilised by high voltage, short duration electrical pulses (electroporation). Drugs will diffuse into porated platelets and become trapped on resealing. We have studied the effects of autologous platelets, electroloaded with the stable prostacyclin analogue, iloprost, on platelet deposition and neointima formation in a pig carotid angioplasty model. Iloprost loaded or control platelets were delivered locally and immediately to the balloon injured site using a double balloon delivery catheter. Acute platelet deposition was measured using ¹¹¹-Indium, and neointima formation at 21 days post angioplasty was assessed by morphometric analysis. In pigs treated with iloprost loaded platelets, platelet deposition on the artery at 2 hours post injury was dramatically reduced (to approximately monolayer coverage), when compared with arteries from pigs treated with control platelets. In pigs with deeply injured arteries, i.e. with extensively ruptured internal elastic lamina (IEL), platelet deposition was reduced by 88% compared with control arteries (118 ± 20 X 10⁶/cm vs. 14 ± 2 X 10⁶/cm, means ± SE, 2P <0.001). In minimally injured arteries (IEL intact) a 65% reduction in platelet deposition was observed (55 ± 24 X 10⁶/cm vs. 19 ± 3X 10⁶/cm, 2P <0.002). A high concentration of free iloprost, delivered to the angioplasty site, with control platelets, had far less effect on platelet deposition, substantiating the advantage of platelet encapsulation. At 21 days post injury, morphometry of the carotid arteries after treatment with iloprost loaded platelets showed significant reductions in intimal area and intimal/medial ratios in minimally injured vessels (P <0.05) as compared with vessels from pigs treated with control platelets. With deeply injured vessels, the mean differences (control vs. treated) for the same morphometric parameters were not significant.

This novel approach of electro-encapsulating drugs within autologous platelets, and using them as highly biocompatible and biodegradable drug targeting vehicles might, with the appropriate choice of encapsulated agent, have potential for reducing the incidence of occlusion after angioplasty and thrombolysis procedures.

• References

• 1 Ross R, Masuda J, Raines E. Cellular interactions, growth factors and smooth muscle cell proliferation in atherogenesis. Ann NY Acad Sci 1990; 598: 102-112
• 2 Forester JS, Fishbein M, Helfant R, Fagin J. A paradigm for restenosis based upon cell biology: Clues for the development of new preventative therapies. In: The Practice of Interventional Cardiology. Vogel JHK, King SB. eds 02. Mosby Year Book Inc; St Louis, USA: 1993. pp 495-508
• 3 Newby AC, George SJ. Proposed roles of growth factors in mediating smooth muscle cell proliferation in vascular pathologies. Cardiovasc Res 1993; 27: 1173-1183
• 4 Clowes AW, Reidy MA, Clowes MM. Mechanisms of stenosis after arterial injury. Lab Invest 1983; 49: 208-215
• 5 Kaplan AV. Local delivery: new directions in restenosis. In: Restenosis Summit VI. Topol EJ. ed Cleveland Clinic Foundation; Ohio, USA: 1994. pp 358-363
• 6 Lincoff AM, Topol AJ, Ellis SG. Local drug delivery for the prevention of restenosis, fact, fantasy and future. Circulation 1994; 90: 2070-2084
• 7 Wolinsky RL, Thung SN. Use of a perforated balloon catheter to deliver concentrated heparin into the wall of the normal canine artery. J Am Coll Cardiol 1990; 15: 475-481
• 8 Hong MK, Wong SC, Farb A, Mehlman MD, Virmani R, Barry JJ, Leon MB. Feasibility and drug delivery efficiency of a new balloon angioplasty catheter for performing simultaneous local drug delivery. Cor Art Dis 1993; 04: 1023-1027
• 9 Azrin MA, Mitchel JF, Alberghini TV, Peck R, Fram DB, Waters D, McKay RG. Effect of local delivery of heparin on platelet deposition during in vivo balloon angioplasty using hydrogel-coated balloons (Abstract). Circulation 1993; 88 (Suppl. 01) 310A
• 10 Hong MK, Wong SC, Popma JJ. A dual purpose angioplasty drug infusion catheter for the treatment of intragraft thrombus. Cathet Cardiovasc Diagn 1994; 32: 193-5
• 11 Gonschior P, Deil S, Maier GR, Dellian M, Goetz AE, Hofling B. Feasibility of local drug application with a new catheter (Abstract). J Am Coll Cardiol 1994; (Suppl. 01) 188A
• 12 Fernandez Ortiz A, Meyer BJ, Mailmac A, Falk E, Badimon L, Fallon JT, Fuster V, Chesbro JM, Badimon JJ. A new approach for intravascular drug delivery: iontophoretic balloon. Circulation 1994; 89: 1518-1522
• 13 Wolinsky RL. The problems and the promise of local drug delivery. In: Restenosis Summit VI. Topol EJ. ed Cleveland Clinic Foundation; Ohio, USA: 1994. pp 352-635
• 14 Hughes K, Crawford N. Reversible electro-permeabilisation of human and rat platelets: evaluation of morphology and functional integrity “in vitro” and “in vivo”. Biochem Biophys Acta 1989; 981: 277-287
• 15 Hughes K, Crawford N. Reversibly electro-permeabilised platelets: potential use as vehicles for drug delivery. Biochem Soc Trans 1990; 18: 871-873
• 16 Fisher CA, Kappa JR, Sinha AK, Cottrell ED, Reiser MJ, Addonizio VP. Comparison of equimolar concentrations of iloprost, prostacyclin and prostaglandin E₁ on human platelet function. J Lab Clin Med 1988; 110: 706-718
• 17 Grant SM, Goa KL. Iloprost: a review of its pharmacodynamic properties and therapeutic potential in peripheral vascular disease, myocardial ischaemia and extra corporeal circulation procedures. Drugs 1992; 43: 889-924
• 18 Pfliegler G, El Gamal BAB, Badimon L, Badimon JJ, Crawford N. Inhibition of platelet recruitment to arterial lesions by predeposition of platelets containing encapsulated iloprost. Thromb Haemost 1994; 72: 604-611
• 19 Crawford N, Chajara J, Pfliegler G, El Gamal BAB, Brewer L, Capron L. Targeting platelets containing encapsulated iloprost to rat aortae during balloon angioplasty. Thromb and Haemost 1995; 73: 535-542
• 20 Heras M, Chesboro JH, Penny WJ, Bailey KR, Badimon L, Fuster V. Effect of thrombin inhibition on the development of platelet-thrombus deposition in pigs. Circulation 1989; 79: 657-675
• 21 Groves PH, Banning AP, Lewis MJ, Cheadle HA, Penny WJ, Newby AC. Smooth muscle cell proliferation and intimal thickening in a porcine model of balloon angioplasty. Atherosclerosis 1995; 117: 83-96
• 22 Bonan R, Paiment P, Scortichini D, Cloutier MJ, Leung TK. Coronary stenosis: evaluation of a restenosis injury index in a swine model. Am Heart J 1993; 126: 334-340
• 23 Penn MS, Saidel GM, Chisholm GM. Relative significance of endothelium and internal elastic lamina in regulating the entry of macromolecules into arteries in vivo. Circ Res 1994; 74: 74-82
• 24 Rosen P, Schwippert B, Kaufman L, Tschope D. Expression of adhesion molecules on the surface of activated platelets is diminished by PGI2 analogues and NO (EDRF) donors: a comparison between healthy and diabetic subjects. Platelets 1994; 05: 42-52
• 25 Chesbro JM, Badimon JJ, Badimon L, Groves N, Fuster V. Arterial angioplasty: Injury, mural thrombus and restenosis. In: The Practice of Interventional Cardiology. Vogel JHK, King SB. eds 02. Mosby Year Book Inc; St Louis, USA: 1981. pp 509-520
• 26 Popma JJ, Topol EJ. Factors influencing restenosis after coronary angioplasty. Amer J Med 1990; 88: 1-16N
• 27 Wilentz JR, Sanborn TA, Haundenschild CC, Valeri CR, Ryan TJ, Faxon DP. Platelet accumulation in experimental angioplasty: time course and relation to injury. Circulation 1987; 75: 636-642
• 28 Fingerle J, Johnson R, Clowes R, Majesky MW, Reidy MA. Role of platelets in smooth muscle cell proliferation and migration after vascular injury in the rat carotid artery. Proc Natl Acad Sci USA 1989; 8: 8412-8416
• 29 Crawford N, Chronos N. Encapsulating drugs within blood platelets: Local delivery to injured arteries during angioplasty. In: Semin Intervent Cardiol. Serruys P, Camenzind E. eds WB Saunders Co Ltd; London: 1996. 01. 91-102
• 30 Hildebrand M. Pharmacokinetics of iloprost and cicaprost in mice. Prostaglandins 1992; 44: 431-442