Comparative Study of Shrinkage in Human Skin, Artificial Human Skin, and Mouse Skin.

INTRODUCTION: The shrinkage of surgical specimens (SS) is known in human skin (HS) but has not been studied in an artificial skin (AS) or mouse skin (MS). OBJECTIVES: To quantify the degree of shrinkage of SS and establish its timing in HS and an in vitro and animal model to explore the possible causes of this phenomenon. METHODOLOGY: We collected 100 SS of HS, 50 SS of AS synthesized with fibrin-agarose biomaterials and 21 SS of MS. The width and length of specimens were measured before the surgical excision (pre-SE), at 5 minutes postsurgery (ex vivo), and after 24 hours of fixation in formalin (postfixation). Histological staining was performed to analyze the differences between HS, AS, and MS that may explain the differences in shrinkage. RESULTS: Between pre-SE and postfixation, the width and length shrank by 16.1% and 17.1% in HS, 14.5% and 8.5% in AS, and 26.5% and 23.1% in MS (P < 0.01), respectively. Shrinkage largely occurred between pre-SE and ex vivo. Cells and interstitial fibers were scant in AS and abundant in MS. CONCLUSIONS: Almost all of the shrinkage occurred during the first 5 minutes postsurgery. According to the AS model findings, 53.6% of SS shrinkage would be explained by the action of dermal fibers and other cellular components of the dermis.

Successful restoration of corneal surface integrity with a tissue-engineered allogeneic implant in severe keratitis patients.

OBJECTIVES: Corneal diseases are among the main causes of blindness, with approximately 4.6 and 23 million patients worldwide suffering from bilateral and unilateral corneal blindness, respectively. The standard treatment for severe corneal diseases is corneal transplantation. However, relevant disadvantages, particularly in high-risk conditions, have focused the attention on the search for alternatives. METHODS: We report interim findings of a phase I-II clinical study evaluating the safety and preliminary efficacy of a tissue-engineered corneal substitute composed of a nanostructured fibrin-agarose biocompatible scaffold combined with allogeneic corneal epithelial and stromal cells (NANOULCOR). 5 subjects (5 eyes) suffering from trophic corneal ulcers refractory to conventional treatments, who combined stromal degradation or fibrosis and limbal stem cell deficiency, were included and treated with this allogeneic anterior corneal substitute. RESULTS: The implant completely covered the corneal surface, and ocular surface inflammation decreased following surgery. Only four adverse reactions were registered, and none of them were severe. No detachment, ulcer relapse nor surgical re-interventions were registered after 2 years of follow-up. No signs of graft rejection, local infection or corneal neovascularization were observed either. Efficacy was measured as a significant postoperative improvement in terms of the eye complication grading scales. Anterior segment optical coherence tomography images revealed a more homogeneous and stable ocular surface, with complete scaffold degradation occurring within 3-12 weeks after surgery. CONCLUSIONS: Our findings suggest that the surgical application of this allogeneic anterior human corneal substitute is feasible and safe, showing partial efficacy in the restoration of the corneal surface.

Successful development and clinical translation of a novel anterior lamellar artificial cornea.

Blindness due to corneal diseases is a common pathology affecting up to 23 million individuals worldwide. The tissue-engineered anterior human cornea, which is currently being tested in a Phase I/II clinical trial to treat severe corneal trophic ulcers with preliminary good feasibility and safety results. This bioartificial cornea is based on a nanostructured fibrin-agarose biomaterial containing human allogeneic stromal keratocytes and cornea epithelial cells, mimicking the human native anterior cornea in terms of optical, mechanical, and biological behavior. This product is manufactured as a clinical-grade tissue engineering product, fulfilling European requirements and regulations. The clinical translation process included several phases: an initial in vitro and in vivo preclinical research plan, including preclinical advice from the Spanish Medicines Agency followed by additional preclinical development, the adaptation of the biofabrication protocols to a good manufacturing practice manufacturing process, including all quality controls required, and the design of an advanced therapy clinical trial. The experimental development and successful translation of advanced therapy medicinal products for clinical application has to overcome many obstacles, especially when undertaken by academia or SMEs. We expect that our experience and research strategy may help future researchers to efficiently transfer their preclinical results into the clinical settings.

A study protocol for a multicentre randomised clinical trial evaluating the safety and feasibility of a bioengineered human allogeneic nanostructured anterior cornea in patients with advanced corneal trophic ulcers refractory to conventional treatment.

INTRODUCTION: There is a need to find alternatives to the use of human donor corneas in transplants because of the limited availability of donor organs, the incidence of graft complications, as well as the inability to successfully perform corneal transplant in patients presenting limbal deficiency, neo-vascularized or thin corneas, etc. We have designed a clinical trial to test a nanostructured fibrin-agarose corneal substitute combining allogeneic cells that mimics the anterior human native cornea in terms of optical, mechanical and biological behaviour. METHODS AND ANALYSIS: This is a phase I-II, randomised, controlled, open-label clinical trial, currently ongoing in ten Spanish hospitals, to evaluate the safety and feasibility, as well as clinical efficacy evidence, of this bioengineered human corneal substitute in adults with severe trophic corneal ulcers refractory to conventional treatment, or with sequelae of previous ulcers. In the initial phase of the trial (n=5), patients were sequentially recruited, with a safety period of 45 days, receiving the bioengineered corneal graft. In the second phase of the trial (currently ongoing), subjects are block randomised (2:1) to receive either the corneal graft (n=10), or amniotic membrane (n=5), as the control treatment. Adverse events, implant status, infection signs and induced neovascularization are evaluated as determinants of safety and feasibility of the bioengineered graft (main outcomes). Study endpoints are measured along a follow-up period of 24 months, including 27 post-implant assessment visits according to a decreasing frequency. Intention to treat, and per protocol, and safety analysis will be performed. ETHICS AND DISSEMINATION: The trial protocol received written approval by the corresponding Ethics Committee and the Spanish Regulatory Authority and is currently recruiting subjects. On completion of the trial, manuscripts with the results of phases I and II of the study will be published in a peer-reviewed journal. TRIAL REGISTRATION: CT.gov identifier: NCT01765244 (Jan2013). EudraCT number: 2010-024290-40 (Dec2012).