Ex vivo expanded corneal limbal stem cell transplantation | Not Recruiting
Ex vivo expanded corneal limbal stem cell transplantation

Trial Source

Health Conditions
  • Severe ocular surface disease arising from limbal stem cell deficiency
Not Recruiting
Recruitment Status
ISRCTN54055321
Primary Trial ID Number
Summary
The cornea is the clear front of the eye and its clarity is vital for the transmission of light to the retina for visual perception. The surface of the cornea is made up of a multi-layered epithelium, which is maintained by adult stem cells located in the periphery of the cornea, in a region known as the limbus. Limbal stem cell deficiency (LSCD) is an irreversible disease resulting from the loss of these corneal epithelial stem cells, or limbal stem cells (LSC), and results in severe ocular surface disease (OSD) characterised by reduced vision or blindness, chronic ocular irritation and visual glare. The corneal epithelium that normally covers the corneal surface becomes deficient and is replaced by the surrounding conjunctival epithelium, resulting in a thickened, irregular, unstable epithelium, often with secondary neovascularisation, inflammatory cell infiltration and disruption of the basement membrane. Conditions that result in OSD from LSCD have a variety of etiologies and can result in profound morbidity for patients. Aniridia is a primary stem cell disorder, but secondary disorders of the LSC are more common e.g. chemical or thermal burns, Stevens-Johnson syndrome, ocular cicatricial pemphigoid, severe contact lens induced keratopathy or chronic use of toxic topical medications. The treatment of patients with severe OSD has been largely unsuccessful, with standard corneal transplantation (penetrating or lamellar keratoplasty) providing a stable ocular surface only for as long as the donor epithelium survives. In addition, this procedure carries the risk of rejection of the transplanted tissue, complications and infection. Even with the current approach based on scientific understanding of the role played by limbal stem cells in corneal surface maintenance, patients still face a very poor prognosis resulting in blindness, redness and pain. It is estimated that there are more than 2000 patients in Scotland alone with corneal blindness due to stem cell deficiency. Several clinical trials have provided evidence to show that grafting viable limbal tissue, either from the fellow healthy eye or a donor eye, with the resident stem cell population may replenish limbal stem cells. However, these techniques have several major limitations. Autologous limbal grafts compromise the healthy donor eyes, while fresh allo-grafts are in short supply and contain Langerhan's and other antigen presenting cells, which increase the risk of graft rejection. Graft materials are stored in organ culture media while the suitability for grafting is evaluated and during this period of storage, limbal stem cells are depleted, rendering the graft material sub-optimal for limbal stem cell transplant. In addition, dissecting a limbal ring transplant from a corneal button is technically demanding and damages the target cell population. Furthermore stem cells are not uniformly distributed around the ring, and it is not always possible to ensure an adequate transfer of stem cells. Advances in tissue engineering techniques have offered a viable alternative to overcome the limitation of limbal tissue available for transplantation. Much interest has been generated by the prospect of re-implanting ex vivo expanded limbal stem cells as a technique to replenish the corneal surface. Human amniotic membrane (AM) is being extensively used in ocular surface disorders and it has been demonstrated that it can be used as a carrier to expand limbal stem cells in vitro before transfer to the ocular surface (Tsai R. et al. 2000). They achieved visual improvement in 6 cases of OSD secondary to chemical burns and pseudopterygium. Other small observational series report success of this technique to reconstruct the ocular surface (Sangwan VS et al. 2003) and a UK study has recently reported successful ocular surface reconstruction following ex vivo expanded corneal limbal cells (Daya SM et al. 2005). However, a major drawback of this study was the use of murine fibroblast 3T3 feeder layers and foetal calf serum to cultivate limbal stem cells, presenting the risk of transmission of animal borne viruses or acquisition of non-human antigenic substances on the cell membrane during culture. Ex vivo expanded limbal stem cells on AM are reconstructed from a known quantity of cells and a viable population of stem cells is assured. In autologous transplantation, only a small piece of tissue is required and cells from donors can be tissue typed, expanded and cryopreserved, allowing matching to the recipient's tissue type. In addition, ex vivo expanded cells on AM are devoid of Langerhan’s cells and other antigen presenting cells, and should, therefore, be less likely to provoke rejection episodes. This pilot study proposes to investigate the possibility of using donor derived ex vivo expanded limbal stem cells on AM as a technique for replenishing the stem cell population and repairing the corneal surface. Amniotic membrane is already used extensively in ocular surface disorders, although AM alone is not effective in treating total stem cell deficiency. However, it is hypothesised that immunosuppressive therapy and AM may allow ocular surface reconstruction by eliminating the inflammatory environment that is detrimental to the function of stem cells. This is the rationale behind using AM alone as the comparator arm on this study. A pilot study is necessary because existing knowledge in this therapeutic technique is still limited and, therefore, the data required for reliable sample size calculations is not currently available. In addition, previous studies have used non-human components in their culture techniques, while this pilot study will facilitate evaluation and optimisation of the use of human serum in the ex vivo expansion of corneal limbal stem cells and allow development of a system without non-human substances in the culture media.
Primary Outcome Measures
  • Best corrected visual acuity
Secondary Outcome Measures
  • 1. Ocular surface score – image analysis based evaluation of area of neovascularisation, area of opacity and degree of abnormal fluorescein staining
  • 2. Quality of Life – as assessed by validated questionnaires VF14 and SF36
  • 3. Successful re-establishment of corneal surface after treatment, defined as absence of corneal vascularisation, absence of goblet cells on the cornea surface, absence of persistent epithelial defects, smooth corneal epithelium and no staining with fluorescein, non-fibrotic and normal limbal anatomy
  • 4. Engraftment of donor cells
Research Question
  • The cornea is the clear front of the eye and its clarity is vital for the transmission of light to the retina for visual perception. The surface of the cornea is made up of a multi-layered epithelium, which is maintained by adult stem cells located in the periphery of the cornea, in a region known as the limbus. Limbal stem cell deficiency (LSCD) is an irreversible disease resulting from the loss of these corneal epithelial stem cells, or limbal stem cells (LSC), and results in severe ocular surface disease (OSD) characterised by reduced vision or blindness, chronic ocular irritation and visual glare. The corneal epithelium that normally covers the corneal surface becomes deficient and is replaced by the surrounding conjunctival epithelium, resulting in a thickened, irregular, unstable epithelium, often with secondary neovascularisation, inflammatory cell infiltration and disruption of the basement membrane. Conditions that result in OSD from LSCD have a variety of etiologies and can result in profound morbidity for patients. Aniridia is a primary stem cell disorder, but secondary disorders of the LSC are more common e.g. chemical or thermal burns, Stevens-Johnson syndrome, ocular cicatricial pemphigoid, severe contact lens induced keratopathy or chronic use of toxic topical medications. The treatment of patients with severe OSD has been largely unsuccessful, with standard corneal transplantation (penetrating or lamellar keratoplasty) providing a stable ocular surface only for as long as the donor epithelium survives. In addition, this procedure carries the risk of rejection of the transplanted tissue, complications and infection. Even with the current approach based on scientific understanding of the role played by limbal stem cells in corneal surface maintenance, patients still face a very poor prognosis resulting in blindness, redness and pain. It is estimated that there are more than 2000 patients in Scotland alone with corneal blindness due to stem cell deficiency. Several clinical trials have provided evidence to show that grafting viable limbal tissue, either from the fellow healthy eye or a donor eye, with the resident stem cell population may replenish limbal stem cells. However, these techniques have several major limitations. Autologous limbal grafts compromise the healthy donor eyes, while fresh allo-grafts are in short supply and contain Langerhan's and other antigen presenting cells, which increase the risk of graft rejection. Graft materials are stored in organ culture media while the suitability for grafting is evaluated and during this period of storage, limbal stem cells are depleted, rendering the graft material sub-optimal for limbal stem cell transplant. In addition, dissecting a limbal ring transplant from a corneal button is technically demanding and damages the target cell population. Furthermore stem cells are not uniformly distributed around the ring, and it is not always possible to ensure an adequate transfer of stem cells. Advances in tissue engineering techniques have offered a viable alternative to overcome the limitation of limbal tissue available for transplantation. Much interest has been generated by the prospect of re-implanting ex vivo expanded limbal stem cells as a technique to replenish the corneal surface. Human amniotic membrane (AM) is being extensively used in ocular surface disorders and it has been demonstrated that it can be used as a carrier to expand limbal stem cells in vitro before transfer to the ocular surface (Tsai R. et al. 2000). They achieved visual improvement in 6 cases of OSD secondary to chemical burns and pseudopterygium. Other small observational series report success of this technique to reconstruct the ocular surface (Sangwan VS et al. 2003) and a UK study has recently reported successful ocular surface reconstruction following ex vivo expanded corneal limbal cells (Daya SM et al. 2005). However, a major drawback of this study was the use of murine fibroblast 3T3 feeder layers and foetal calf serum to cultivate limbal stem cells, presenting the risk of transmission of animal borne viruses or acquisition of non-human antigenic substances on the cell membrane during culture. Ex vivo expanded limbal stem cells on AM are reconstructed from a known quantity of cells and a viable population of stem cells is assured. In autologous transplantation, only a small piece of tissue is required and cells from donors can be tissue typed, expanded and cryopreserved, allowing matching to the recipient's tissue type. In addition, ex vivo expanded cells on AM are devoid of Langerhan’s cells and other antigen presenting cells, and should, therefore, be less likely to provoke rejection episodes. This pilot study proposes to investigate the possibility of using donor derived ex vivo expanded limbal stem cells on AM as a technique for replenishing the stem cell population and repairing the corneal surface. Amniotic membrane is already used extensively in ocular surface disorders, although AM alone is not effective in treating total stem cell deficiency. However, it is hypothesised that immunosuppressive therapy and AM may allow ocular surface reconstruction by eliminating the inflammatory environment that is detrimental to the function of stem cells. This is the rationale behind using AM alone as the comparator arm on this study. A pilot study is necessary because existing knowledge in this therapeutic technique is still limited and, therefore, the data required for reliable sample size calculations is not currently available. In addition, previous studies have used non-human components in their culture techniques, while this pilot study will facilitate evaluation and optimisation of the use of human serum in the ex vivo expansion of corneal limbal stem cells and allow development of a system without non-human substances in the culture media.
Design Type
Sorry, this information is not available
Ethics Approval
North of Scotland Research Ethics Committee, 22 June 2011 (amendment to protocol approved 08 August 2011) ref: 11/AL/0298
Publications
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Countries of Recruitment
United Kingdom
Participant Sex
Both
Participant Age Range
Adult
Participant Type
Patient
Trial Sample Size
20
Participant Inclusion Criteria
  • 1. Adult patients, of either sex, with corneal blindness due to limbal stem cell deficiency
  • 2. Best corrected visual acuity of 6/18 or less in the worse affected eye. No restriction on best corrected visual acuity in the better eye
  • 3. Severe, debilitating corneal disease with extremely low chance of successful outcome with limbal and corneal graft surgery
  • 4. Functioning retina indicated by light perception and ultra-sonographic examination to exclude retinal detachment
  • 5. Normal intra-ocular pressure
  • 6. Schirmer’s test at least 50% normal values
Participant Exclusion Criteria
  • 1. Inability to give informed, comprehending consent
  • 2. Unfitness for local or general anaesthesia or to give an autologous serum donation
  • 3. Inability to self-administer medication
  • 4. Inability to tolerate immunosuppressive therapy
  • 5. Severe dry eyes
  • 6. Patients with corneal anaesthesia
  • 7. Patients with severe lid deformities
  • 8. Patients with uncontrolled glaucoma or drainage procedures
  • 9. Patients who test positive for any standard donor marker of infection
  • 10. Female patients of a child bearing age who are pregnant, lactating, or not taking adequate contraception
Interventions
One group of patients will receive donor derived ex vivo expanded corneal limbal stem cells and immunosuppressive therapy, and the second group will receive amniotic membrane graft and immunosuppressive therapy.
Design Details
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Study Design
Randomised controlled single blind pilot study
Results Reporting
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Acronym
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Scientific Title
Pilot clinical assessment of ex vivo expanded corneal limbal stem cell transplantation in patients with severe ocular surface diseases arising from limbal stem cell deficiency
Secondary Trial Identifying Number
LSC-001
Website
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Study Funded By
UK Stem Cell Foundation (UK) ref: LSC-001
Funder Type
Sorry, this information is not available
Study Sponsored By
NHS Lothian (UK)
Study Also Sponsored By
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Primary Sponsor Type
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Secondary Sponsor Type
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Key Dates

Date of First Enrollment

01 Feb 2012

Recruitment End Date

31 Dec 2014

Trial End Date

31 Dec 2014

Date added to Registry

28 Mar 2012

Last Updated

28 Mar 2012