Three-dimensional insights into dermal tissue as a cue for cellular behavior

The biological applications of DNA nanomaterials: current challenges and future directions

DNA, a genetic material, has been employed in different scientific directions for various biological applications as driven by DNA nanotechnology in the past decades, including tissue regeneration, disease prevention, inflammation inhibition, bioimaging, biosensing, diagnosis, antitumor drug delivery, and therapeutics. With the rapid progress in DNA nanotechnology, multitudinous DNA nanomaterials have been designed with different shape and size based on the classic Watson-Crick base-pairing for molecular self-assembly. Some DNA materials could functionally change cell biological behaviors, such as cell migration, cell proliferation, cell differentiation, autophagy, and anti-inflammatory effects. Some single-stranded DNAs (ssDNAs) or RNAs with secondary structures via self-pairing, named aptamer, possess the ability of targeting, which are selected by systematic evolution of ligands by exponential enrichment (SELEX) and applied for tumor targeted diagnosis and treatment. Some DNA nanomaterials with three-dimensional (3D) nanostructures and stable structures are investigated as drug carrier systems to delivery multiple antitumor medicine or gene therapeutic agents. While the functional DNA nanostructures have promoted the development of the DNA nanotechnology with innovative designs and preparation strategies, and also proved with great potential in the biological and medical use, there is still a long way to go for the eventual application of DNA materials in real life. Here in this review, we conducted a comprehensive survey of the structural development history of various DNA nanomaterials, introduced the principles of different DNA nanomaterials, summarized their biological applications in different fields, and discussed the current challenges and further directions that could help to achieve their applications in the future.

Fractal analysis of rat dermal tissue in the different injury states

Scar formation and chronic ulcers can develop following a skin injury. They are the result of the over- or underproduction of collagen. It is very important to evaluate the quality and quantity of the collagen that is produced during wound healing, especially with respect to its structure, as these factors are very important to a complicated outcome. However, there is no standard way to quantitatively analyse dermal collagen. As prior work characterised some potentially fractal properties of collagen, it was hypothesised that collagen structure could be evaluated with fractal dimension analysis. Small-angle X-ray scattering technology (SAXS) was used to evaluate the dermis of rats exposed to graft harvest, burn, and diabetic pathologic states. It was found that almost all collagen structures could be quantitatively measured with fractal dimension analysis. Further, there were significant differences in the three-dimensional (3-D) structure of normal collagen versus that measured in pathologic tissues. There was a significant difference in the 3-D structure of collagen at different stages of healing. The findings of this work suggest that fractal analysis is a good tool for wound healing analysis, and that quantitative collagen analysis is very useful for assessing the structure of dermal collagen.

Microarchitectural analysis of decellularised unscarred and scarred dermis provides insight into the organisation and ultrastructure of the human skin with implications for future dermal substitute scaffold design

The three-dimensional spatial arrangement of dermal tissue plays a crucial role in directing cellular behaviour during wound healing. It is vital to elucidate a better understanding of the three-dimensional dermal architecture of human skin. We sought to understand the configuration in morphological structure of decellularised human dermis between unscarred skin and normotrophic scars. Skin biopsies underwent decellularisation (DNA removal = 88%). Histological analysis showed no change in gross morphology of decellularised unscarred and scarred dermis. Multiphoton and atomic force microscopies showed that collagen fibres in unscarred decellularised dermis were interwoven akin to a mesh-like structure. Collagen fibres in decellularised unscarred dermis were less stiff (mean: 2.155 ± 0.9595 MPa; p < 0.0001) with a rougher ( Rq = 16.5, Ra = 12.5, Rmax = 198; p < 0.0001) surface topography. Scarred dermis had a higher collagen volume density (papillary dermis, p < 0.0082; reticular dermis, p < 0.0332). The results demonstrate that scaffolds should exhibit a mesh-like structure with a biomimetic surface and low stiffness.

Flat Incision Technique for Reconstructive Brow Surgery: A Wound Healing Model and Clinical Evaluation

Background:

Skin incision is considered to be placed at 90° in reference to the skin to get perfect wound edge adaptation. The incision on hair-bearing tissues, as the scalp, is considered to be bevelled at 45° to promote hair growth through the scar. There is no consensus about the preferred incision angle on the brow. The aim of this article was to demonstrate the feasibility of the “flat incision technique” for brow repositioning, where brow deformation results after forehead reconstruction. A wound-healing model for the bevelled incision is presented.

Methods:

Brow incisions are bevelled with an angle of 20°. The lower incision is placed inside the brow so that the upper 2 rows of hair are included; the dermis is completely transected and dissection is continued into the subdermal plane. The procedure is presented in a patient who underwent resection of the forehead due to melanoma.

Results:

The bevelled incision increases the surface area of dermal layer by a factor of 2 compared with the standard vertical skin incision at 90°. Loss of the dermal tissue integrity and continuity due to trauma hinders the recovery of cell migration and function, resulting in a more prominent scar formation. It appears reasonable that with the increased surface area of the dermal layers in the wound edges, the scar quality improves. The case study demonstrates the feasibility of the procedure.

Conclusion:

The bevelled 20° incision for brow repositioning and reshaping showed to be a viable and predictable procedure.