ULTRASTRUCTURAL-STUDY OF THE CORNEA IN A BONE MARROW-TRANSPLANTED HURLER-SYNDROME PATIENT

This case report describes a 14-year-old girl with Hurler syndrome, wh o had received a successful bone marrow-transplant at the age of two. Corneal clouding was present at the time of transplant and has only pa rtially cleared. A right penetrating keratoplasty was performed and th e corneal specimen was examined by light microscopy, transmission elec tron microscopy with Cuprolinic blue staining for proteoglycans, and l ow-angle X-ray diffraction. The results show the corneal stroma to be disrupted by vacuolated stromal cells. There is abnormal accumulation of proteoglycans in the vacuolated stromal cells and nearby stroma. Th ese proteoglycans mainly contain chondroitin/dermatan sulphate glycosa minoglycans since they are susceptible to chondroitinase ABC. There ar e a large range of fibril diameters (12.5-50.1 nm) and there is an abn ormal distribution of the fibril diameters measured from micrographs. Both are confirmed by X-ray diffraction results (the mean collagen fib ril diameters are in a range between 29.7 and > 51.1 nm). X-ray diffra ction also shows that the mean centre-to-centre distance of the fibril s slightly increases. These findings suggest that proteoglycans play a role in modelling the stromal structure and can also explain the corn eal clouding. Many long-spacing collagen structures with a mean period icity of 91.8 nm are observed in the corneal stroma. The finding that the long-spacing collagen consists of fine collagen fibrils and that v ery few proteoglycans filaments bind to them suggests that some change in the interaction of proteoglycans and collagen is responsible for t he formation of long-spacing collagen. To our knowledge, this is the f irst ultrastructural study of the cornea from a bone marrow-transplant patient with Hurler syndrome. The structural features documented here relate to a cornea incompletely corrected by bone marrow transplantat ion. (C) 1996 Academic Press Limited