Amniotic Membrane Transplantation for Limbal Stem Cell Deficiency

The maintenance of a healthy functional corneal epithelium is provided by a unique subpopulation of stem cells located in the limbal region (1). When limbal epithelial stem cells are destroyed or become dysfunctional, a pathological state known as limbal stem cell deficiency (LSCD) manifests. The hallmark of LSCD is the conjunctivalization of the cornea (2), and is frequently associated with superficial vascularization and compromised corneal surface (3).

LSCD can be found with a number of corneal diseases such as chemical burns, Stevens Johnson syndrome, aniridia, peripheral keratitis, severe limbitis, etc (for more details see Table 1). Patients with LSCD suffer from a severe loss of vision and annoying photophobia, and cannot be corrected by conventional PKP. Therefore, it is important to accurately diagnose LSCD because erroneous diagnosis may subject the patient to unnecessary surgeries.  Correct diagnosis, which may require the use of impression cytology, will lead to reconstruction with limbal stem cell transplantation.

Table 1: Corneal diseases with LSCD

[To obtain an Impression Cytology (IC) kit, please contact Dr. Tseng (

stseng@ocularsurface.com), who has established the Impression Cytology Core Laboratory at the Ocular Surface Center which is certified by State of Florida (No. 800017632) and the Clinical Laboratory Improvement Amendment 1998 (CLIA) (No. 10D1004176) effective 9/20/2002.] 

Partial LSCD

For eyes with partial LSCD, where a part of the limbal circumference is damaged, the corneal surface can be reconstructed by debridement of conjunctivalized epithelium with (4) or without (5) transplantation of cryopreserved amniotic membrane  as shown in Figure 1 and Video 1.

Figure 1: Partial LSCD presented as psuedopterygium and treated with excision and Amniotic Membrane Transplantation (AMT)
            Before treatment                      After treatment
  


Video 1: Click here to view the AMT procedure for partial LSCD

Click here for detailed surgical instruction for treating partial LSCD with AMT.

Total LSCD: Unilateral

For eyes inflected with total LSCD; where the entire limbal circumference is damaged, corneal surface reconstruction resorts to transplantation of limbal epithelial stem cells (6). When total LSCD involves only one eye, successful reconstruction can be achieved by transplanting autologous limbal epithelial stem cells from the fellow eye in a procedure termed “conjunctival limbal autograft (CLAU)” as shown in Figure 2 and Video 2 below.(7) Because the source of limbal epithelial stem cells is autologous, there is no risk of immune rejection and hence no need for systemic immunosuppression.

Figure 2: Unilateral total LSCD treated with superficial keratectomy AMT & CLAU
           Before treatment                    After treatment


Video 2: Click here to view the procedure for AMT with CLAU 

Click here for detailed surgical instruction for treating total LSCD with AMT and CLAU.

Total LSCD: Bilateral

In cases of bilateral total LSCD, a keratolimbal allograft (KLAL) (Figure 2) is used and the success is dictated by effective immunosuppression (8) as shown below in Figure 3 and Video 3.

Figure 3:  Bilateral total LSCD treated with superficial keratectomy AMT & KLAL
          Before treatment                    After treatment

Video 3: Click here to view the procedure for AMT & KLAL

Click here for detailed surgical instruction for AMT & KLAL for total LSCD.

Other Considerations in Treating LSCD

For complex diseases associated with LSCD, it is important to restore the ocular surface’s defenses first so a stable tear film can be maintained before limbal stem cell transplantation (Figure 4). For eyes with conjunctival inflammation or cicatricial complications such as pathogenic symblepharon, it is important to correct these deficiencies before surgically transplanting limbal epithelial stem cells as described  above. Click here to view surgical strategies for symblepharon lysis and fornix reconstruction using cryopreserved amniotic membrane. 

Figure 4: General strategies of Ocular Surface Reconstruction

Adjunctive use of amniotic membrane (AM) has beneficial effects which help preserve and expand the transplanted limbal stem cell population. These benefits include the restoration of an intact basement membrane which supports epithelial cell adhesion, differentiation, and migration (9) while suppressing epithelial cell apoptosis.(10)

Because AM supports the growth of epithelial progenitor cells by prolonging their life span and maintaining their clonogenincity, 11 AM has also been used for ex vivo expansion of limbal stem cells, (11-12) as a sole treatment for partial LSCD, (4) in acute stage of chemical burn (13) and also as an adjunctive procedure in stem cell transplantation such as keratolimbal allograft (KLAL) (8) and donor and/or recipient sites of conjunctival limbal autograft (CLAU) (14-15). In these cases, AM not only promotes epithelialization, but also reduces inflammation, neovascularization and scar formation (16-17).

Click here to view a list of supplies for surgically treating LSCD.

Click here for Postoperative Considerations for patients receiving LSCD treatment.

References:

1. Cotsarelis G, Cheng SZ, Dong G, Sun T-T, Lavker RM. Existence of slow-cycling limbal epithelial basal cells that can be preferentially stimulated to proliferate: implications on epithelial stem cells. Cell 1989;57:201-209.

2. Puangsricharern V, Tseng SCG. Cytologic evidence of corneal diseases with limbal stem cell deficiency. Ophthalmology 1995;102:1476-1485.

3. Dua HS, Jagjit SS, Azuara-Blanco A, Gupta P. Limbal stem cell deficiency: concept, aetiology, clinical presentation, diagnosis and management. Indian J Ophthalmol 2000;48:83-92.

4. Anderson DF, Ellies P, Pires RT, Tseng SC. Amniotic membrane transplantation for partial limbal stem cell deficiency. Br J Ophthalmol 2001;85:567-575.

5. Dua HS. The conjunctiva in corneal epithelial wound healing. Br J Ophthalmol 1998;82:1407-1411.

6. Tseng SCG, Prabhasawat P, Barton K, Gray T, Meller D. Amniotic membrane transplantation with or without limbal allografts for corneal surface reconstruction in patients with limbal stem cell deficiency. Arch Ophthalmol 1998;116:431-441.

7. Kenyon KR, Tseng SC. Limbal autograft transplantation for ocular surface disorders. Ophthalmology 1989;96:709-722.

8. Espana EM, Di Pascuale M, Grueterich M, Solomon A, Tseng SC. Keratolimbal allograft in corneal reconstruction. Eye 2004;18:406-417.

9. Tseng SC, Tsubota K. Important concepts for treating ocular surface and tear disorders. Am J Ophthalmol 1997;124:825-835.

10. Boudreau N, Sympson CJ, Werb Z, Bissell MJ. Suppression of ICE and apoptosis in mammary epithelial cells by extracellular matrix. Science 1995;267:891-893.

11. Meller D, Pires RTF, Tseng SCG. Ex vivo preservation and expansion of human limbal epithelial stem cells on amniotic membrane cultures. Br J Ophthalmol 2002;86:463-471.

12. Nakamura T, Koizumi N, Tsuzuki M, Inoki K, Sano Y, Sotozono C, Kinoshita S. Successful regrafting of cultivated corneal epithelium using amniotic membrane as a carrier in severe ocular surface disease. Cornea 2003;22:70-71.

13. Meller D, Pires RTF, Mack RJS, Figueiredo F, Heiligenhaus A, Park WC, Prabhasawat P, John T, McLeod SD, Steuhl KP, Tseng SCG. Amniotic membrane transplantation for acute chemical or thermal burns. Ophthalmology 2000;107:980-990.

14. Meallet MA, Espana EM, Grueterich M, Ti S-E, Goto E, Tseng SCG. Amniotic membrane transplantation for recipient and donor eyes undergoing conjunctival limbal autograft for total limbal stem cell deficiency. Ophthalmology 2003;110:1585-1592.

15. Kobayashi A, Shirao Y, Yoshita T, Yagami K, Segawa Y, Kawasaki K, Shozu M, Tseng SCG. Temporary amniotic membrane patching for acute chemical burns. Eye 2003;17:149-158.

16. Tseng SCG, Espana EM, Kawakita T, Di Pascuale MA, Wei Z-G, He H, Liu TS, Cho TH, Gao YY, Yeh LK, Liu C-Y. How does amniotic membrane work? The Ocular Surface 2004;2:177-187.

17. Dua HS, Gomes JA, King AJ, Maharajan VS. The amniotic membrane in ophthalmology. Surv Ophthalmol 2004;49:51-77.