Red light accelerates the formation of a human dermal equivalent.
- 1 Programa de Pós-Graduação Interunidades Bioengenharia – EESC/FMRP/IQSC, 67817 Universidade São Paulo-São Carlos-SP , Brazil.
- 2 Instituto de Química de São Carlos, 67817 Universidade de São Paulo-São Carlos-SP , Brazil.
- 3 Instituto de Física de São Carlos, Universidade de São Paulo-São Carlos-SP, Brazil.
Development of biomaterials’ substitutes and/or equivalents to mimic normal tissue is a current challenge in tissue engineering. Thus, three-dimensional cell culture using type I collagen as a polymeric matrix cell support designed to promote cell proliferation and differentiation was employed to create a dermal equivalent in vitro, as well to evaluate the photobiomodulation using red light. Polymeric matrix cell support was prepared from porcine serous collagen (1.1%) hydrolyzed for 96 h. The biomaterial exhibited porosity of 95%, a median pore of 44 µm and channels with an average distance between the walls of 78 ± 14 µm. The absorption of culture medium was 95%, and the sponge showed no cytotoxicity to Vero cells, a non-tumor cell line. Additionally, it was observed that irradiation with light at 630 nm (fluency 30J/cm-2) leads to the cellular photobiomodulation in both monolayer and human dermal equivalent (three-dimensional cell culture system). It was also verified that the cells cultured in the presence of the polymeric matrix cell support, allows differentiation and extracellular matrix secretion. Therefore, the results showed that the collagen sponge used as polymeric matrix cell support and the photobiomodulation at 630 nm are efficient for the production of a reconstructed human dermal equivalent in vitro.
Effect of low–level laser treatment of tissue-engineered skin substitutes: contraction of collagen lattices.
- Exploit Technologies, Biomedical Sciences Division, Agency of Science and Technology (A STAR), 30 Biopolis Street, Singapore 138671, Singapore.
Fibroblast-populated collagen lattices (FPCL) are widely used in tissue-engineered artificial skin substitutes, but their main drawback is that interaction of fibroblasts and matrix causes contraction of the lattice, reducing it to about 20% of its original area. The effect of low–levellaser treatment (LLLT) on the behavior of 3T3 fibroblasts seeded in collagen lattices containing 20% chondroitin-6-sulphate was investigated to determine whether LLLT could control the contraction of FPCL. A He-Ne laser was used at 632.8 nm to deliver a 5-mW continuous wave with fluences from 1 to 4 J/cm(2). Laser treatment at 3 J/cm(2) increased contraction of collagen lattices in the absence of cells but decreased contraction of cell seeded lattices over a 7-day period. The effect was energy dependent and was not observed at 1, 2, or 4 J/cm(2). There was no alteration in fibroblast viability, morphology, or mitochondrial membrane potential after any laser treatments, but the distribution of actin fibers within the cells and collagen fibers in the matrices was disturbed at 3 J/cm(2). These effects contribute to the decrease in contraction observed. LLLT may offer a means to control contraction of FPCL used as artificial skin substitutes.
[Primary grafting research of tissue engineered oral mucosa lamina propria on skin full thickness wounds].
- Department of Oral Surgery, 2nd Hospital of China Medical University, Shenyang Liaoning 110004, P R China. Lauwuzq@sina.com
To study the allograft effect of two kinds of tissue engineered oral mucosa lamina propria on skin full-thickness wounds.
The cultured Wistar rat oral mucosa fibroblasts (OMF) were incorporated into collagen or chitosan-collagen to construct the tissue engineered oral mucosa lamina propria, and then the OMFs were labeled with BrdU. The full-thickness round skin defects were made with a round knife (diameter, 0.8 cm) on the backs of 36 Wistar rats (21-25 weeks old), which were divided into 2 experimental groups: the fibroblast-populated collagen lattices (FPCL) group (grafted by FPCLs) and the fibroblast-populated chitosan collagen lattices (FPCCL) group (grafted by FPCCLs), and the control group (only covered with gauges). All the wounds were observed by the naked eyes or the light microscope, and were measured 4, 7, 14, and 21 days postoperatively.
There were no infection during the wound healing period. At 7 days after the grafting, the wounds in the 3 groups were covered by scab and/or gauze; at 14 days, the gauze and scab on the wounds in the three groups were all replaced by the new epidermis naturally except one scab each in the FPCCL group and the control groups, which was replaced at 17 days. All the centers of the new epidermis were measurable as the pink red points. At 21 days, all the new skins were smooth without hairs, and their color was similar to the normal one. At 4, 7, and 14 days, there was an indication that the wound diameters became significantly smaller in the three groups; but after the 14th day, there was no significant indication of this kind. At 7 days, the wound diameter in the FPCL group was significantly smaller than that in the FPCCL group and the control group (P < 0.01). Under the light microscope, at 4 days postoperatively, the decayed tissue on the surfaces of the recipient wounds in the FPCL group and the FPCCL group was separated from the lower granular tissue in which there were many inflammatory cells, fibroblasts, and new vessels. There was a similar phenomenon in the control group. Each skin wound in the three groups was only partly keratinocytes at 7 days postoperatively. The recipient wounds were wholly keratinocytes with when rete ridges observed at 14 and 21 days, but in the control group the wounds were keratinocytes with no rete ridges. Fibers in the new dermis were thin. The OMFs with Brdu appeared in the granular tissue and new dermis at 4, 7, 14, and 21 days postoperatively, which could be illustrated by the immunohistochemical staining. The positive OMFs and the granular tissue joined in the repair of the skin defects without any allergic reaction during the period of the wound healing.
The oral mucosa fibroblasts as the new seed cells can join in the repair of the skin defects effectively and feasible. The fibroblast-populated collagen lattices and the fibroblast-populated chitosan collagen lattices can repair skin defects effectively and feasible, too. And the quality of the new skins was better in the two experimental groups than in the control group.