Table 1.

Summary of the approaches to generate vascularized nerve grafts/conduits and some example studies.

Method	Nerve type and its source of vascularization	Species	Nerve gap	Time point	Outcomes compared with controls	Reference
Vascularized nerve grafts	Vascularized sural nerve graft	Human	50–80 mm	2–41 months	No control Sensitivity was recovered in a satisfactory manner The patients were satisfied with their treatment outcomes	(Rose and Kowalski, 1985)
	Sciatic nerve graft with proximal preserved pedicle	Rabbit	45 mm	5–15 weeks	Conventional nonvascularized sciatic nerve graft as a control Improved remyelination Increased number of axonal fibers	(Restrepo et al., 1985)
	Rabbit median nerve graft with brachial vessels	Rabbit	30 mm	10 and 24 weeks	Conventional nonvascularized median nerve graft as a control Greater muscle contraction force and number of axons No statistical difference in CMAP area and muscle weight	(Shibata et al., 1988)
	Rat sciatic nerve with caudal femoral vessels	Rat	15 mm	1–24 weeks	Free sciatic nerve graft as a control Faster motor nerve conduction velocity Greater density of regenerated axons	(Koshima and Harii, 1985)
Vascularized grafts by vascular implantation	Implanting an arteriovenous fistula into the sciatic nerve	Rat	N/A	N/A	N/A	(Cavadas and Vera‐Sempere, 1994)
	Peripheral nerve graft was placed into the groove between the femoral artery and vein for 14 days	Rabbit	N/A	N/A	N/A	(Saray et al., 2002)
	PGA nerve conduit vascularized by host superficial inferior epigastric (SIE) for 14 days	Rat	15 mm	1–18 weeks	Nonvascularized conduit graft and an autograft as controls Better functional outcomes andmore myelinated axons than that of the novascularized conduit group Did not achieve the level of reinnervation of autograft	(Iijima et al., 2016)
	Amnion tube placed in contact with the femoral artery and vein for 3 weeks	Rat	10 mm	3 months	Nonvascularized amnion tube as a control Higher number of axons Larger axon diameters Thicker myelin sheath	(Ozcan et al., 1993)
Blood vessels‐including tubulation	Insertion of a subcutaneous artery and sciatic nerve in a silicone tube	Rat	5 mm	4, 8, and 15 weeks	Silicone tube only as a control Contain more capillaries than the control More functional and morphological recovery of regenerating nerve	(Kosaka, 1990)
	Silicone tube containing sural vessels	Rat	25 mm	12 and 24 weeks	No control Axons able to regenerate across the gap Reinnervate the tibialis anterior muscle 6 months after operation	(Kakinoki et al., 1997)
	Silicone tube with a subcutaneous artery adjacent to the injured nerve	Human	30–50 mm	6–9 months	No control Out of nine nerves, with a follow‐up of 6–9 months, the results were excellent in five nerves, good in two and poor in two	(Yong‐xiang and Ti‐pei, 1992)
Vascularized biogenic conduits	Silicone rod placed near a sciatic nerve for 8 weeks	Rat	15 mm	8 weeks	Nonvascularized biological conduit as a control Vascularized conduit had significantly improved mean peak amplitudes of the CMAPs No statistical difference between the groups in terms of latencies The myelinated axonal counts was significantly higher	(Yapici et al., 2017)
	In vivo formation of biogenic conduit after 4 weeks of implantation parallel to the sciatic nerve	Rat	15 mm	1, 2, 3, and 4 weeks	Autologous nerve graft as a control All groups showed an increase of SFI after 4 weeks with no significant difference Significant higher intraneural amount of fibrous tissue in biogenic conduit Myelin sheaths were thicker	(Penna et al., 2011)
	Silicone rubber rod left in situ for at least 3 weeks	Rat	10–12 mm	3 months	No control Good functional recovery of motor fibers	(Lundborg and Hansson, 1980)
	Pseudosheath formed around the silicone tube during the first stage is used as a tunnel to envelope the median nerve graft segment in the second stage	Rat	15 mm	3, 6, and 15 weeks	Conventional median nerve graft as a control Reflex latency was significantly lower than the conventional nerve graft Higher vascularity	(Zadegan et al., 2015)

“N/A” indicates that there is no results of an in vivo assessment of the construct.

Abbreviations: CMAP, compound muscle action potential; SFI, sciatic functional index.