Profile of biological characterizations and clinical application of corneal stem/progenitor cells

Table 1 Culture conditions of limbal stem cells

Culture condition	Canine amniotic membrane	Atelocollagen gel	Temperature-responsive culture dish
Culture
Adhesion time, d	1	1	2
Convergence time, d	5	7	14
Layers	6-8	4-5	2-3
Immunofluorescence
Ki-67	Basal layer +	Basal layer ++	Basal layer -
K3	Each layer +	Each layer except basal layer +	Each layer +
ABCG2	Only in basal layer +
P63	Basal layer +	2-3 layers, including the basal layer +	Basal layer +

Table 2 Methods for the isolation of limbal stem cells

Experimenter	Tissue	Isolation methods	Medium	Markers
Yamamoto et al[42], 2010	Human corneal epithelial stem/progenitor cells	0.25% collagenase and accumax	Serum-free PCT corneal epithelium medium	P75 ntr2, p63, integrin β-1
Albert et al[171], 2012	Human cornea limbal epithelial stem cells	None	Human lens capsule	KRT8, KRT14, KRT3, KRT12, KRT19, VIM, MKI67, p63α, ABCG2, CK19, Vim, Itgα9, CK8/18, CK14
Shaharuddin et al[43], 2014	Human limbal epithelial cell	LSP protocol, Hoechst 33342 dye, Flow Cytometry Analysis and Fluorescence Activated Cell Sorting	None	ABCG2, ΔNp63, Sox2
Nam et al[44], 2013	Beagle limbal epithelial cells	None	Canine amniotic membrane	ABCG2, p63, vimentin
Moriyama et al[45], 2014	Equine corneal epithelial stem cells	Dispase II and a 0.25% trypsin EDTA solution	Standard supplemented hormone epithelial medium	P63, CK14
Nam et al[46], 2015	Beagle limbal epithelial cells	Dispase II, trypsin	Canine amniotic membrane; atelocollagen gel; temperature-responsive culture dish	Ki-67, K3, ABCG2, P63
López-Paniagua et al[60], 2016	Human cornea limbal epithelial stem cells	0.25% trypsin-EDTA	Biosafe IOBA-HS culture medium	K14, K15, ABCG2, p63α
Shirzadeh et al[61], 2018	Human cornea limbal epithelial stem cells	Collagenase II and cold trypsin	Supplemental hormonal epithelial medium with husscs or 3T3 cells as feeder layers	ABCG2, ΔNP63-α, CK19, CK 3, CK12
Li et al[62], 2021	Human cornea limbal epithelial stem cells	0.05% trypsin/1 mm EDTA solution	Standard supplemented hormone epithelial medium	TSPAN7, SOX17

SHEM: Supplemented hormone epithelial medium.

Table 3 Causes of limbal stem cell deficiency

Item	Causes
Hereditary LSCD	Congenital aniridia[80,81]
	Dyskeratosis congenital[82,83]
	Xeroderma pigmentosum[84]
	Peters’ anomaly[85]
	Keratitis ichthyosis deafness syndrome[86]
	Epidermolysis bullosa[87]
Acquired LSCD	Acquired nonimmune-mediated	Burns	Alkali burns[88,89]
			Acid burns[90,91]
			Thermal burns[92,93]
			Radiation burns[94]
		Infection	Viral keratitis[95]
			Bacterial keratitis[96]
			Trachoma[97,98]
		Oncologic	Ocular surface tumours[99]
		Iatrogenic	Cryotherapy[84,100]
			Chemotherapeutic agents[101-103]
			Surgeries in the limbic region[103,104]
		Others	Contact lens use[105,106]
			Bullous keratopathy[107]
	Acquired primary immune-mediated	Stevens-Johnson syndrome[108]
		Mucous membrane pemphigoid[109,110]
		Vernal keratoconjunctivitis[111,112]
		Atopic keratoconjunctivitis[113]
		Graft-versus-host disease[114,115]

LSCD: Limbal stem cells deficiency.

Table 4 Treatment strategies for limbal stem cell deficiency

Treatment	Description
Conservative treatment	Nonsurgical options	Autologous serum drops
		Therapeutic soft contact lens
		Therapeutic scleral lens
		Eye lubrication
	Surgical options	Corneal scraping
		Amniotic membrane transplantation
Invasive treatment	Conjunctival limbal autograft
	Conjunctival limbal allograft
	Keratolimbal allograft
	Ex vivo cultivated limbal epithelial stem cells
	Simple limbal epithelial transplantation
	Emerging alternative cell populations transplantation	Alternative cell populations	Oral mucosal epithelial cells
			Human embryonic stem cells
			Induced pluripotent stem cells
			Mesenchymal stem cells
			Human immature dental pulp stem cells
		Alternative cell carriers/scaffolds	Modified HAM
			Collagen
			Fibrin
			Siloxane hydrogel contact lenses
			Human lens capsule
			Poly (ε-caprolactone)
			Onion epithelial membrane scaffolds
			Carboxymethyl cellulose
			Electrospun polycaprolactone/gelatine nanocomposites