Decellularized adipose matrix provides an inductive microenvironment for stem cells in tissue regeneration.

Stem cells play a key role in tissue regeneration due to their self-renewal and multidirectional differentiation, which are continuously regulated by signals from the extracellular matrix (ECM) microenvironment. Therefore, the unique biological and physical characteristics of the ECM are important determinants of stem cell behavior. Although the acellular ECM of specific tissues and organs (such as the skin, heart, cartilage, and lung) can mimic the natural microenvironment required for stem cell differentiation, the lack of donor sources restricts their development. With the rapid development of adipose tissue engineering, decellularized adipose matrix (DAM) has attracted much attention due to its wide range of sources and good regeneration capacity. Protocols for DAM preparation involve various physical, chemical, and biological methods. Different combinations of these methods may have different impacts on the structure and composition of DAM, which in turn interfere with the growth and differentiation of stem cells. This is a narrative review about DAM. We summarize the methods for decellularizing and sterilizing adipose tissue, and the impact of these methods on the biological and physical properties of DAM. In addition, we also analyze the application of different forms of DAM with or without stem cells in tissue regeneration (such as adipose tissue), repair (such as wounds, cartilage, bone, and nerves), in vitro bionic systems, clinical trials, and other disease research.

Ocular surface changes in type II diabetic patients with proliferative diabetic retinopathy.

AIM: To detect and analyze the changes on ocular surface and tear function in type II diabetic patients with proliferative diabetic retinopathy (PDR), an advanced stage of diabetic retinopathy (DR), using conventional ophthalmic tests and the high-resolution laser scanning confocal microscopy. METHODS: Fifty-eight patients with type II diabetes were selected. Based on the diagnostic criteria and stage classification of DR, the patients were divided into the non-DR (NDR) group and the PDR group. Thirty-six patients with cataract but no other ocular and systemic disease were included as non-diabetic controls. All the patients were subjected to the conventional clinical tests of corneal sensitivity, Schirmer I Test, and corneal fluorescein staining. The non-invasive tear film break-up time (NIBUT) and tear interferometry were conducted by a Tearscope Plus. The morphology of corneal epithelia and nerve fibers was examined using the high-resolution confocal microscopy. RESULTS: The NDR group exhibited significantly declined corneal sensitivity and Schirmer I test value, as compared to the non-diabetic controls (P< 0.001). The PDR group showed significantly reduced corneal sensitivity, Schirmer I test value, and NIBUT in comparison to the non-diabetic controls (P < 0.001). Corneal fluorescein staining revealed the progressively injured corneal epithelia in the PDR patients. Moreover, significant decrease in the corneal epithelial density and morphological abnormalities in the corneal epithelia and nerve fibers were also observed in the PDR patients. CONCLUSION: Ocular surface changes, including blunted corneal sensitivity, reduced tear secretion, tear film dysfunction, progressive loss of corneal epithelia and degeneration of nerve fibers, are common in type II diabetic patients, particularly in the diabetic patients with PDR. The corneal sensitivity, fluorescein staining scores, and the density of corneal epithelial cells and nerve fibers in the diabetic patients correlate with the duration of diabetes. Therefore, ocular surface of the patients with PDR should be examined regularly by conventional approaches and confocal microscopy to facilitate early diagnosis and treatment of keratopathy.

[Effect of lamellar keratoplasty time on the production of serum specific antibody in corneal alkali burns].

OBJECTIVE: To observe the production of serum specific anti-denatured corneal antibody and the effects of lamellar keratoplasty on changes of corneal histopathology in different stages after alkali burns. METHODS: 20 male New Zealand rabbits, with alkali burns in right eye were randomly divided into 5 groups including: burned group; 2 early lamellar keratoplasty group (operation at 3 or 7 days post alkali burns respectively); 2 middle and later lamellar keratoplasty groups (operation at 2 or 5 weeks after alkali burns respectively). The level of serum specific antibody in each group was detected by ELISA and the corneal structure was evaluated by light and electron microscopy in different stages after alkali burns. RESULTS: The anti-denatured corneal antibody was induced after corneal alkali burns. The level of antibody significantly increased at 2th week post, peaking burn at 5 or 6th week, then decreasing. More antibodies were detected when contralateral eye was burn at 8 week post first burn. However, only slight increasing antibody was detected in early lamellar keratoplasty group. Furthermore, no significant changes of antibody production were observed in middle and later lamellar keratoplasty group. The light and electron microscopic analysis showed that, the corneal epithelium recovered better, the fibre of corneal stroma arranged better, inflammatory cells infiltrated less and neovascularization formed less in lamellar keratoplasty groups comparing to the burned group. The early lamellar keratoplasty groups recovered better than in middle and later lamellar keratoplasty groups. CONCLUSION: Early lamellar keratoplasty after corneal alkali burns can significantly decrease the immune response. Histopathological data also indicate that early lamellar keratoplasty can improve the tissue regeneration and recovery, prevent topical inflammatory reaction, and abate corneal neovascularization. This study suggests that early lamellar keratoplasty is more effective than the conservative treatment.