Table 9.

Preclinical efficacy data and accompanying xenogeneic rejection mechanism of pig-to-NHP corneal xenotransplantation.

References	Type	Donor pig breed/GE	Graft size (mm)/Thickness (㎛)		Survival days	Immunosuppression	Histology, AH and blood changes in NHPs with the rejected grafts
Amano et al. (2003)	ALK	Domestic/WT	5.0/100-200		>30,>30, >30, 75, 165, 180	None	•CD4+ & CD8+ T cells & macrophages at 6 M •Macrophages at 1 M •No NK cell at 1 M
Zhiqiang et al. (2007)	ALK	WZS miniature/WT	6.0/anterior half		>90, >90, >90, >90	None	•Inflammatory cells
Li et al. (2011)	ALK	WZS miniature/WT	7.0/anterior half		180, 15, 180,180,180	None	•Eosinophils, lymphocytes
Choi et al. (2011b)	ALK	SNU miniature/WT	7.5/312.5–375		>398, >194, 24.5, 24.5	Topical, subconjunctival, and systemic steroid	•CD8+ T cells & macrophages » CD4+ T & B cells •Deposition of C3c •Aqueous C3a ↑ at 4 W •Effector CD8+ T cells, donor pig–specific IgG ↑ (blood)
Vabres et al. (2014)	ALK	Large White/WT	6.5/350-400		9,70,21,21	Topical steroid	•Macrophages, CD4+ T cells > B cells •Focal Ig M and C3c deposits •Preformed anti-αGal & anti-non-αGal Ig M & Ig G (plasma) •Ig M & Ig G xenoreactive Ab↑ (plasma) •Complement-dependent cytotoxicity against donor cell (serum)
Kim et al. (2017)	DALK	SNU miniature/WT	7.5/687.5–750		>389, >382, >236, >201, >61	Topical, subconjunctival, and systemic steroid + IVIG + Anti-CD40 Ab	•CD4+ & CD8+ T cells, B cells & macrophages ↑ (They were scarcely found in the accepted grafts) •IgG/C3c deposits ↑ (IgG deposits ↓ in the accepted grafts) •No increase in AH C3a with the accepted grafts •CD28−CD95+ CD4+ & CD8+ T cells ↓ with accepted grafts (blood)
Vabres et al. (2014)	ALK	Large White/hCTLA4-Ig transgenic	6.5/350-400		21,50, 90,120	Topical steroid	•Macrophages, CD4+ T & B cells •Ig M & Ig G xenoAb↑ with hCTLA4-Ig transgenic donor pig (plasma) •Complement-dependent cytotoxicity against donor cell (serum)
	ALK	Sus scrofa/GT-KO + hCD39 + hCD55 + hCD59 + FT	6.5/350-400		9,34
Zhiqiang et al. (2007)	PKP	WZS miniature/WT	6.0/Full		12, 16, 16, 16, 12, 18	None	•A few inflammatory cells
	PKP	WZS miniature/WT	6.0/Full		129, 276, 182, 144	Subconjunctival steroid	•Few inflammatory cells
Jie et al. (2013)	PKP	WZS miniature/WT	6.0/Full		32, 42, 40, 34, 38, 30	Systemic cyclophosphamide + BMT	•Low levels of inflammatory cells •No eosinophil •Ig A & C3c lower than in control (serum)
	PKP	WZS miniature/WT	6.0/Full		12, 18, 16, 20, 20, 20	Systemic cyclophosphamide	•Eosinophils ↑↑ •Ig A & C3c ↑(serum)
Choi et al. (2015)	PKP	SNU miniature/WT	8.0/Full		21,28,29	Topical, subconjunctival, and systemic steroid	•Macrophages, B & CD8+ T cells » CD4+ T cells •Ig G and C3c deposition •Expression of αGal ↑ •Anti-αGal Ig M/Ig G ↑ (plasma) •Donor pig-specific Ig G ↑ (plasma) •AH C3a, IFNγ, TNFα, IL-2, IL-12, IL-4, IL-5, IP-10, MCP-1, RANTES ↑
					>933, >243, 318, >192	Topical, subconjunctival, and systemic steroid + Anti-CD154 Ab	•Few inflammatory cells •Less Ig G & C3c deposition •Expression of αGal ↓↓
Dong et al. (2017)	PKP	Large White·Landrace/WT	6.5/Full	157, 28, 92, 33		Topical and subconjunctival steroid	•Inflammatory cells at the junction •CD3+ T cells •No CD4+ & CD8+ T & B cell, macrophage •Anti-αGal & non-αGal Ig G/Ig M ↑ (plasma) •Donor pig-specific Ig G/Ig M ↑ (plasma)
		Large White·Landrace/GT-KO + CD46		128, 57, 47, 171			•Inflammatory cells at the junction •CD3+ T cells •No CD4+ & CD8+ T & B cell, macrophage •Non-αGal Ig G/Ig M ↑ (plasma) •Donor pig-specific Ig G/Ig M ↑ (plasma)
Lee et al. (2017b)	PKP	Large White/GT-KO + CD46	6.5/Full	>90, >90, >90,>90		Topical, subconjunctival, and systemic steroid	•Retrocorneal membranes originated from donor
Kim et al. (2018a)	PKP	SNU miniature/WT	7.5/Full	41, >196, >203, >273, >422 > 511		Topical, subconjunctival, and systemic steroid + IVIG + Anti-CD40 Ab	•CD4+ & CD8+ T & B cells & macrophages ↑ (They were barely seen in the accepted grafts) •Anti-donor specific IgG↑ (plasma)
				97>, 134, >184, >210, >260, 297, >470		Topical, subconjunctival, and systemic steroid + Tacrolimusa + IVIG + Basiliximab + Anti-CD20 Abb
Yoon et al. (2019)	PKP	SNU miniature/WT	7.5/Full	56, 92, 162, >181, >182, >182,>198		Topical, subconjunctival, and systemic steroid + Tacrolimusc + IVIG + Basiliximab + Anti-CD20 Abd	•CD8+IFNγ+ T cells ↑↑at 2 W (blood) •AH & plasma C3a↑↑ •Donor specific Ig G↑↑ (plasma) •Anti-αGal Ig G↑↑ (plasma)
				29, 149, 161		Topical, subconjunctival, and systemic steroid + Tacrolimuse + IVIG + Basiliximab
Yoon et al. (2020)	PKP	White Yucatan/GK-KO or GT-KO + hCD39	7.5/Full	37, 55, 72, 91, 165b		Topical, subconjunctival, and systemic steroid + Tacrolimuse	•CD4+ & CD8+ T & B cells & macrophages •AH C3a & plasma anti-non-αGaI IgG ↑ •Depositions of C3c and Ig G •Retrocorneal membrane originated from recipient
		White Yucatan/GT-KO or GT + CMAH + iGb3s triple KO		>83, >187, >187, >375		Topical, subconjunctival, and systemic Steroid + Tacrolimusa + IVIG + Basiliximab + Anti-CD20 Abb	•Few inflammatory cells. •No change of anti-non-αGaI Ig G (plasma) •Less high AH C3a than in control
Liu et al. (2019)	DSAEK	WZS miniature/WT	6.0/posterior lamellara	<30, <30, >58, >180, >180, >270, >298		Topical and subconjunctival steroid	•CD4+, CD8+, CD68+ cells •Scarce B cells •Depositions of C3c and Ig G •Ig M/Ig G anti-αGal ↑(plasma) •AH IL-6 ↑

Abbreviations: Ab: antibody, αGal: Galα1-3Galβ1-4GlcNAc-R, AH: aqueous humor, ALK: anterior lamellar keratoplasty, BMT: bone marrow transplantation, C3c & C3a: component of complement fragment, CD: cluster of differentiation, CMAH: cytidine monophospho-N-acetylneuraminic acid hydroxylase, DALK: deep anterior lamellar keratoplasty, DSAEK: Descemet stripping automated endothelial keratoplasty, FT: fucosyltransferase, GE: genetically-engineered, GT: α1,3-galactosyltransferase, GT-KO: α1,3-galactosyltransferase gene-knockout, hCTLA4-Ig: human cytotoxic T-lymphocyte associated antigen 4-immunoglobulin, hCD39: human ectonucleoside triphosphate diphosphohydrolase-1, hCD46: human complementary regulatory protein, hCD55: human complement decay-accelerating factor, hCD59: human MAC-inhibitory protein, iGb3s: isoglobotrihexosylceramide 3 synthase, IVIG: intravenous immunoglobulin, IFNγ: interferon gamma, IL: interleukin, IP-10: interferon gamma-induced protein, PKP: penetrating keratoplasty, MCP: monocyte chemoattractant protein, M: months, RANTES: regulated upon activation normal T cell expressed and secreted, SNU: Seoul National University, TNFα: tumor necrosis factor-α, W: weeks, WZS: Wuzhishan, WT: wild-type.

Tacrolimus was intramuscularly administered twice daily at a dose of 0.05^a or 0.035^c mg/kg or at a dose of 0.05 mg/kg for 4 weeks followed by 0.035 mg/kg^e.

Anti-CD20 Ab was intravenously administered at a dose of 20 mg/kg on postoperative days 0 and 7, and every 2^b or 3^d months.

^aPosterior lamellar graft was made after removal of anterior lamellae by 510 ㎛.

^bOne corneal graft that survived 165 days was derived from a pig of the crossbreeding Landrace with Chicago minipig.