Tissue reactions of in situ formed dextran hydrogels crosslinked by stereocomplex formation after subcutaneous implantation in rats

The purpose of the study. The estimation of skin microcirculatory changes appearing in rats after subcutaneous implantation of polycaprolactone (PCL) scaffolds. Materials and methods. The experiments were conducted on 3 groups of rats: comparison group - the animals exposed to surgical intervention to the extent equivalent to matrix implantation, negative control group - animals subcutaneously implanted with non-biocompatible matrix; and experimental - rats subcutaneously implanted by PCL-scaffold. Skin microcirculation was analyzed by Lazer Doppler flowmetry (LDF) on the 7th, 14th and 21st day of the experiment. Morphological analysis of soft tissue complex and matrix samples was carried out on the 21st day of the experiment for scaffold biocompatibility verification. Results. It has been found that moderate increase in skin perfusion of animals in the comparison group over the surgical intervention area is not accompanied by the changes of active mechanisms of blood flow modulation and is completely resolved by the 21st day of the experiment. In negative control group, skin perfusion over the implantation area is 2 times higher than in controls in the period from 7th to 21st day of the experiment and this is accompanied by the significant increase of neurogenic and myogenic blood flow oscillation amplitudes. In the course of morphological analysis, these animals have demonstrated active inflammatory response. In the experimental group, perfusion changes are comparable with those in the comparison group and they resolve completely by the 21st day of the experiment. Morphological analysis suggests that by the 21st day of the experiment PLC-scaffold is evenly colonized by connective tissue cells and is vascularized. At the same time, reactive changes of adjacent tissues have not been detected. Conclusion. Skin microcirculatory changes over the scaffold implantation area correspond to the morphological pattern of tissue reactions which allows using LDF for dynamic estimation of scaffold biocompatibility in the course of subcutaneous implantation tests. This data suggest good PLC-scaffold biocompatibility which proves the prospects of its practical application in the tissue engineering.

Download Full-text

Comparative Histological and Morphometric Autopsy Study of Femora and Acetabula with Stable Cemented Hip Prostheses

Hip International ◽

10.1177/112070000301300205 ◽

2003 ◽

Vol 13 (2) ◽

pp. 86-93 ◽

Cited By ~ 1

Author(s):

I. Bos

Keyword(s):

Wear Particles ◽

Prosthesis Loosening ◽

Autopsy Study ◽

Hip Prostheses ◽

Autopsy Specimens ◽

Tissue Reactions ◽

Acetabular Components ◽

Insight Into ◽

Short Implant

To gain insight into the tissue reactions leading to non-infectious prosthesis loosening autopsy specimens of 9 stable cemented femoral and acetabular components 1 to 16 years in situ were analysed histomorphologically and morphometrically. In femora and acetabula, bone and cement were separated by an interface membrane composed of connective tissue and granulation tissue after short implant duration. After longer implant duration, infiltrates of macrophages containing wear particles of the bone cement and – though less abundant – polyethylene predominated. The interface membranes of the acetabula appeared three times as broad as in proximal parts of the femora. They showed no topographical variations. In the femora, however, the membranes were proximally considerably thicker than in distal parts. In both femora and acetabula, the adjacent spongiosa were infiltrated by macrophages as well. The cancellous bone showed remodelling with formation of a neocortical layer at the border between the spongiosa and the interface membrane. Focal metaplastic formation of cartilage was also present. The results indicate that in femora and acetabula, basically analogous mechanisms lead to non-infectious late loosening, which is connected with the accumulation of wear particles and macrophages in the interface membrane. A positive correlation of the width of the interface membrane with the implant duration was found only in the acetabulum. This could explain the comparatively frequent socket loosening.

Download Full-text

Radiographic evaluation of hip resurfacing: the role of x-rays in the diagnosis of a problematic resurfaced hip

Hip International ◽

10.1177/1120700019836373 ◽

2019 ◽

Vol 30 (2) ◽

pp. 167-175

Author(s):

Catherine Van Der Straeten ◽

Alessandro Calistri ◽

George Grammatopoulos ◽

Koen De Smet

Keyword(s):

Metal Ions ◽

Female Gender ◽

Hip Resurfacing ◽

Radiographic Evaluation ◽

X Rays ◽

Radiographic Findings ◽

Clinical Scores ◽

Soft Tissue Reactions ◽

Tissue Reactions

Introduction: Hip resurfacing (HRA) requires a new standardised radiographic evaluation protocol. Evaluation of acetabular components is similar to total hip arthroplasty (THA) but femoral components require different criteria. This study evaluates the efficacy of a new femoral zonal system for radiographic HRA assessment in identifying clinical problems. Methods: A new proximal femoral zonal system divides implant-cement-bone interfaces at head and neck into 7 DeSmet zones. 611 in situ and 100 revised HRA were assessed for component positioning, borderline findings (reactive lines, cortical thickening, cancellous condensation) or sinister findings (lucent lines, bone resorption, osteolysis). Findings were correlated with gender, size, implant survival, clinical scores, metal ions, and adverse soft tissue reactions (ALTR). Results: Radiological changes were found in 265 hips (37.3%), 154 sinister (21.7%) and 111 borderline (15.6%). 84% of revisions had sinister findings versus 11.4% of in situ HRA ( p < 0.001). The mean number of abnormal acetabular and femoral zones was 3.3 in revised compared to 0.6 in situ HRA ( p < 0.001). Sinister findings were associated with female gender, lower clinical scores, smaller sizes or ASR design (all: p < 0.001). Metal ions were higher with sinister ( p < 0.001) and borderline ( p < 0.01) findings compared to normal radiographs. Pathological findings in ⩾4 zones had a sensitivity of 50% and specificity of 94.2% (AUC = 0.898) in detecting hips with ALTR (odds ratio = 49). Conclusion: In order to accurately evaluate progressive radiographic changes in HRA, specific zones have been established around the femoral component. There was a high correlation between radiographic findings and outcome measures. 84% of problematic hips and 90.4% of proven ALTR had sinister changes.

Download Full-text

Different Tissue Reactions to Activated Carbon Fivers - Pathological and Immunological Findings after Subcutaneous Implantation -

Molecular Crystals and Liquid Crystals ◽

10.1080/714965462 ◽

2002 ◽

Vol 388 (1) ◽

pp. 167-171 ◽

Cited By ~ 7

Author(s):

Shozo Koyama ◽

Satoshi Tanaka ◽

Yoshihiro Yamaguchi ◽

Hisao Haniu ◽

Genichi Konishi ◽

...

Keyword(s):

Activated Carbon ◽

Subcutaneous Implantation ◽

Tissue Reactions

Download Full-text

Ex Vivo and In Vivo Analysis of a Novel Porcine Aortic Patch for Vascular Reconstruction

International Journal of Molecular Sciences ◽

10.3390/ijms22147623 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7623

Author(s):

Ignacio Stöwe ◽

Jens Pissarek ◽

Pia Moosmann ◽

Annica Pröhl ◽

Sven Pantermehl ◽

...

Keyword(s):

Bacterial Infections ◽

Tissue Reaction ◽

Host Tissue ◽

Graft Material ◽

Cellular Infiltration ◽

Subcutaneous Implantation ◽

Tissue Integration ◽

Immune Tissue ◽

Tissue Reactions ◽

Implantation Model

(1) Background: The aim of the present study was the biocompatibility analysis of a novel xenogeneic vascular graft material (PAP) based on native collagen won from porcine aorta using the subcutaneous implantation model up to 120 days post implantationem. As a control, an already commercially available collagen-based vessel graft (XenoSure®) based on bovine pericardium was used. Another focus was to analyze the (ultra-) structure and the purification effort. (2) Methods: Established methodologies such as the histological material analysis and the conduct of the subcutaneous implantation model in Wistar rats were applied. Moreover, established methods combining histological, immunohistochemical, and histomorphometrical procedures were applied to analyze the tissue reactions to the vessel graft materials, including the induction of pro- and anti-inflammatory macrophages to test the immune response. (3) Results: The results showed that the PAP implants induced a special cellular infiltration and host tissue integration based on its three different parts based on the different layers of the donor tissue. Thereby, these material parts induced a vascularization pattern that branches to all parts of the graft and altogether a balanced immune tissue reaction in contrast to the control material. (4) Conclusions: PAP implants seemed to be advantageous in many aspects: (i) cellular infiltration and host tissue integration, (ii) vascularization pattern that branches to all parts of the graft, and (iii) balanced immune tissue reaction that can result in less scar tissue and enhanced integrative healing patterns. Moreover, the unique trans-implant vascularization can provide unprecedented anti-infection properties that can avoid material-related bacterial infections.

Download Full-text

Rendez vous with Saturn's rings

International Astronomical Union Colloquium ◽

10.1017/s0252921100101885 ◽

1984 ◽

Vol 75 ◽

pp. 743-759 ◽

Cited By ~ 2

Author(s):

Kerry T. Nock

Keyword(s):

Solar Energy ◽

Electric Propulsion ◽

Power Source ◽

Propulsion System ◽

Low Thrust ◽

Ring Plane ◽

The Earth ◽

Total Impulse ◽

Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

Download Full-text