Macrophages: From Simple Phagocyte to an Integrative Regulatory Cell for Inflammation and Tissue Regeneration-A Review of the Literature.

The understanding of macrophages and their pathophysiological role has dramatically changed within the last decades. Macrophages represent a very interesting cell type with regard to biomaterial-based tissue engineering and regeneration. In this context, macrophages play a crucial role in the biocompatibility and degradation of implanted biomaterials. Furthermore, a better understanding of the functionality of macrophages opens perspectives for potential guidance and modulation to turn inflammation into regeneration. Such knowledge may help to improve not only the biocompatibility of scaffold materials but also the integration, maturation, and preservation of scaffold-cell constructs or induce regeneration. Nowadays, macrophages are classified into two subpopulations, the classically activated macrophages (M1 macrophages) with pro-inflammatory properties and the alternatively activated macrophages (M2 macrophages) with anti-inflammatory properties. The present narrative review gives an overview of the different functions of macrophages and summarizes the recent state of knowledge regarding different types of macrophages and their functions, with special emphasis on tissue engineering and tissue regeneration.

Interim Storage of Biospecimen at Satellite Collection Centers: Dewar and Cryotube Choice Are Important for Temporary Storage in Liquid Nitrogen.

One major goal of biobanks is to provide the best possible biospecimen quality for research use. This can be achieved, notably in accredited structures, by using standardized procedures for collection, processing, and storage of biosamples and associated data. Since tissue samples of a clinical biobank are commonly collected at surgical theaters in satellite locations or hospitals in remote areas, adequate temporary storage of the biosample is mandatory to maintain optimal sample quality. In cases where immediate snap freezing of the collected material is possible, interim storage of the samples in portable dewars filled with liquid nitrogen (LN2) is a widely used method. Therefore, the ideal dewar size and maximum storage time need to be considered to maintain an optimal biospecimen quality. In addition, the nature of the cryotube material is an important aspect for keeping the biosample safe while storing it in LN2. The objective of this study was to test different dewar vessels with respect to LN2 volume and consumption and to analyze the impact of LN2 contact on cryotube material through scanning electron microscopy.

In Vivo Comparison of Synthetic Macroporous Filamentous and Sponge-like Skin Substitute Matrices Reveals Morphometric Features of the Foreign Body Reaction According to 3D Biomaterial Designs.

Synthetic macroporous biomaterials are widely used in the field of skin tissue engineering to mimic membrane functions of the native dermis. Biomaterial designs can be subclassified with respect to their shape in fibrous designs, namely fibers, meshes or fleeces, respectively, and porous designs, such as sponges and foams. However, synthetic matrices often have limitations regarding unfavorable foreign body responses (FBRs). Severe FBRs can result in unfavorable disintegration and rejection of an implant, whereas mild FBRs can lead to an acceptable integration of a biomaterial. In this context, comparative in vivo studies of different three-dimensional (3D) matrix designs are rare. Especially, the differences regarding FBRs between synthetically derived filamentous fleeces and sponge-like constructs are unknown. In the present study, the FBRs on two 3D matrix designs were explored after 25 days of subcutaneous implantation in a porcine model. Cellular reactions were quantified histopathologically to investigate in which way the FBR is influenced by the biomaterial architecture. Our results show that FBR metrics (polymorph-nucleated cells and fibrotic reactions) were significantly affected according to the matrix designs. Our findings contribute to a better understanding of the 3D matrix tissue interactions and can be useful for future developments of synthetically derived skin substitute biomaterials.

Semiautomated quantification of the fibrous tissue response to complex three-dimensional filamentous scaffolds using digital image analysis.

Fibrosis represents a relevant response to the implantation of biomaterials, which occurs not only at the tissue-material interface (fibrotic encapsulation) but also within the void fraction of complex three-dimensional (3D) biomaterial constructions (fibrotic ingrowth). Usual evaluation of the biocompatibility mostly depicts fibrosis at the interface of the biomaterial using semiquantitative scores. Here, the relations between encapsulation and infiltrating fibrotic growth are poorly represented. Virtual pathology and digital image analysis provide new strategies to assess fibrosis in a more differentiated way. In this study, we adopted a method previously used to quantify fibrosis in visceral organs to the quantification of fibrosis to 3D biomaterials. In a proof-of-concept study, we transferred the "Collagen Proportionate Area" (CPA) analysis from hepatology to the field of biomaterials. As one task of an experimental animal study, we used CPA analysis to quantify the fibrotic ingrowth into a filamentous scaffold after subcutaneous implantation. We were able to demonstrate that the application of the CPA analysis is well suited as an additional fibrosis evaluation strategy for new biomaterial constructions. The CPA method can contribute to a better understanding of the fibrotic interactions between 3D scaffolds and the host tissue responses.

Compared DNA and RNA quality of breast cancer biobanking samples after long-term storage protocols in - 80 °C and liquid nitrogen.

Molecular investigations are crucial for further developments in precision medicine. RNA sequencing, alone or in combination with further omic-analyses, resulted in new therapeutic strategies. In this context, biobanks represent infrastructures to store tissue samples and body fluids in combination with clinical data to promote research for new predictive and prognostic biomarkers as well as therapeutic candidate molecules. Until today, the optimal storage conditions are a matter of debate especially with view to the storage temperature. In this unique approach we compared parallel samples from the same tumour, one half stored at - 80 °C and one half in the vapor phase of liquid nitrogen, with almost identical pre-analytical conditions. We demonstrated that RNA isolated from breast cancer samples revealed significantly higher RINe-values after 10 years of storage in the vapor phase of liquid nitrogen compared to storage at - 80 °C. In contrast, no significant difference was found regarding the DIN-values after DNA isolation. Morphological changes of the nucleus and cytoplasm, especially in the samples stored at - 80 °C, gave insights to degenerative effects, most possibly due to the storage protocol and its respective peculiarities. In addition, our results indicate that exact point-to point documentation beginning at the sample preparation is mandatory.

Physiological and Pathophysiological Aspects of Primary Cilia-A Literature Review with View on Functional and Structural Relationships in Cartilage.

Cilia are cellular organelles that project from the cell. They occur in nearly all non-hematopoietic tissues and have different functions in different tissues. In mesenchymal tissues primary cilia play a crucial role in the adequate morphogenesis during embryological development. In mature articular cartilage, primary cilia fulfil chemo- and mechanosensitive functions to adapt the cellular mechanisms on extracellular changes and thus, maintain tissue homeostasis and morphometry. Ciliary abnormalities in osteoarthritic cartilage could represent pathophysiological relationships between ciliary dysfunction and tissue deformation. Nevertheless, the molecular and pathophysiological relationships of 'Primary Cilia' (PC) in the context of osteoarthritis is not yet fully understood. The present review focuses on the current knowledge about PC and provide a short but not exhaustive overview of their role in cartilage.

[Histological diagnostics in joint pathology due to increasing regenerative therapeutic strategies - special consideration for cartilage damage]. / Histologische Diagnostik in der Gelenkpathologie in Zeiten rekonstruktiver Therapieverfahren ­ besondere Berücksichtigung der Knorpelschäden.

Orthopedic and trauma surgery are currently confronted with significant changes in their interventional and therapeutic strategies, especially in knee surgery. Minimally invasive and reconstructive techniques lead not only to modifications of the repertoire of interventional methods but also of the indications and questions for histopathological diagnostics. The classical problems in knee surgery remain important issues, which are traumatic, degenerative, and infectious lesions. In addition, questions regarding regeneration and integration of cell-material constructs will become more and more important in the future. Furthermore, questions regarding the regenerative potential of an implantation site for such constructs and the morphological quality of harvested tissue for the in vitro cell expansion of autologous cells are becoming increasingly important. The autologous chondrocyte transplantation is a good example of the relevance of the histopathological re-evaluation of the regenerated tissue for a better understanding of the pathophysiology of reconstructive therapies. It becomes clear that for specific aims based on reconstructive therapies, new scoring systems should be established for the histopathological routine diagnostic service. Furthermore, there is need for the definition of further histopathological criteria, which will help to optimize the differential application of reconstructive strategies via tissue engineering. The present report gives a short overview of the modifying requirements on the histopathological diagnostics in specimens from knee-surgery but does not claim to be exhaustive.