Table 3.

Examples of pre-clinical and clinical tests on biodegradable polymers and metals.

Implant	Implant Site and Time	Major Test Results
PLLA Igaki-Tamai stent (with ST638 or ST494) [48]	Porcine coronary arteries, 21d	Neointimal formation and geometric remodeling were significantly less at the ST638-loaded stent site than at the ST494 site.
Igaki-Tamai stent [49]	Human patient artery, 6 months to 10 years	No stent thrombosis and no major cardiac event occurred within 30 days. No major cardiac event, except for repeat angioplasty, developed within 6 months. Long-term (>10 years) clinical outcomes showed acceptable major adverse cardiac events and scaffold thrombosis rates without stent recoil and vessel remodeling.
PLLA stent[50]	Porcine Coronary Artery, 16 weeks	Histological examination revealed no inflammation and minimal neointimal hyperplasia
Copolymeric polylactide stent[51]	Rabbit aorta, 34 months	No inflammatory reaction observed after 6 months and it was completely degraded by 24 months.
Paclitaxel-eluting PDLLA[52]	Porcine coronary arteries, 3 months	The histomorphometric analysis at 3 weeks demonstrated inhibition of neointimal formation by 53% with the paclitaxel-loaded PDLLA when compared to the PDLLA stent, and by 44% when compared to metal stents.
Pure Fe stent [40]	Rabbits (descending aorta), 6–18 months	No thrombogenicity, no significant neointimal proliferation and systemic toxicity, faster degradation at junctions of the stent
Pure Fe stent [53]	Porcine (descending aorta), 360 d	Degradation product adjacent to the stent struts and within adventitia accompanied by macrophages; no sign of toxicity
Pure Fe stent [54]	Pig coronary artery, 28d	Fe stent is very safe
Pure Fe wire [12]	Rat (artery lumen or artery matrix), 1–9 months	Fe wire experienced substantial corrosion within artery matrix, whereas it experienced minimal biocorrosion in blood-contacting environment
AE21[2] (Mg alloy)	Pig (coronary artery), 56d	Mg alloy is satisfactory; 40% loss of perfused lumen diameter due to neointima formation; degradation time needs to be extended
WE43 [55] (Mg alloy)	Minipig (coronary artery), 56d	Mg alloy stents are safe and reliable; the struts are covered by neointima after 6 d; higher minimal lumen diameter on week 4 and 12 than the 316L stent group
WE 43 [56]	Domestic (28d) or minipigs Pig (coronary artery, 3 months)	Degradation after 28 d post-surgery; less neointima compare to 316L stent; stenosis increased from 28 d to 3 months; decreased lumen area
WE43 [57]	Domestic pig coronary artery,28d	Reduced endothelial proliferation, presence of gas pockets
Mg stent [58]	Left pulmonary artery of a preterm baby patient, 5 months	Complete degradation occurred during 5 months; no in-stent obstruction or neointimal hypertrophy was observed; the degradation level was tolerated and the stent secured reperfusion of the previously occluded left pulmonary artery.