Assessment of mesenchymal stem cell effect on foreign body response induced by intraperitoneally implanted alginate spheres.

Foreign body response to implanted hydrogels and consequently fibrotic overgrowth on implanted spheres will decrease in vivo performance of these biomaterials. Considering the previous reports related to the immune-privileged properties of mesenchymal stem cells (MSCs), we hypothesized that encapsulated human placenta-derived MSCs (HP-MSCs) will mitigate the foreign body response against alginate hydrogels. The HP-MSC-laden alginate hydrogel was cross-linked with a CaCl2 solution. Morphological and mechanical properties of alginate spheres were determined by scanning electron microscopy imaging, degradation, and swelling tests. The HP-MSC-laden alginate spheres or cell-free spheres were implanted into the peritoneal cavity of BALB/c mice. After intraperitoneal implantation of spheres into BALB/c mice over a period of 14 days, capsules were recovered and precapsular fibrotic tissue on their surfaces was investigated. Assessment of encapsulated HP-MSC viability using acridine orange/propidium iodide staining revealed that foreign body response against cell-laden hydrogel results in fibrous overgrowth on spheres and consequently leads to the HP-MSC necrosis. In spite of immunomodulatory effects of MSCs, the introduction of spheres into the body induces foreign body response that affects the viability of immuno-isolated HP-MSCs during 14-day posttransplant period. The presence of HP-MSCs within alginate hydrogel could not reduce the fibrotic overgrowth on spheres compared with cell-free spheres. Therefore, there is an essential need for hydrogels that mitigate the foreign body response as a key challenge in the development of tissue engineering and drug delivery technologies.

In vivo biocompatibility assessment of poly (ether imide) electrospun scaffolds.

Poly(ether imide) (PEI), which can be chemically functionalized with biologically active ligands, has emerged as a potential biomaterial for medical implants. Electrospun PEI scaffolds have shown advantageous properties, such as enhanced endothelial cell adherence, proliferation and low platelet adhesion in in vitro experiments. In this study, the in vivo behaviour of electrospun PEI scaffolds and PEI films was examined in a murine subcutaneous implantation model. Electrospun PEI scaffolds and films were surgically implanted subcutaneously in the dorsae of mice. The surrounding subcutaneous tissue response was examined via histopathological examination at 7 and 28 days after implantation. No serious adverse events were observed for both types of PEI implants. The presence of macrophages or foreign body giant cells in the vicinity of the implants and the formation of a fibrous capsule indicated a normal foreign body reaction towards PEI films and scaffolds. Capsule thickness and inflammatory infiltration cells significantly decreased for PEI scaffolds during days 7-28 while remaining unchanged for PEI films. The infiltration of cells into the implant was observed for PEI scaffolds 7 days after implantation and remained stable until 28 days of implantation. Additionally some, but not all, PEI scaffold implants induced the formation of functional blood vessels in the vicinity of the implants. Conclusively, this study demonstrates the in vivo biocompatibility of PEI implants, with favourable properties of electrospun PEI scaffolds regarding tissue integration and wound healing. Copyright © 2015 John Wiley & Sons, Ltd.

Long-term outcomes of type I thyroplasty with silicone implantation: Assessment of excised laryngeal tissue from a patient with secondary hypopharyngeal carcinoma.

Here we describe the long-term outcomes of type I thyroplasty (TP-I) with silicone block implantation through histopathological assessments in a male patient who underwent pharyngolaryngectomy for secondary hypopharyngeal carcinoma 7 years after silicone implantation. A 66-year-old man presented with esophageal carcinoma and underwent subtotal esophagotomy. Subsequently, his left vocal fold exhibited fixation in a paramedian position, and he underwent TP-I with silicone block implantation 2 years after the primary esophageal surgery. His voice quality improved; however, he developed glottic carcinoma in the right vocal fold 6 months after TP-I and underwent laser cordectomy. Glottic carcinoma recurred 21 months later, and he underwent laser cordectomy again. Five years after the second laser surgery, he underwent pharyngolaryngectomy and neck dissection for hypopharyngeal carcinoma detected in the right pyriform sinus. We histopathologically examined a horizontal section of the resected larynx to assess silicone implant-related changes. Although migration of the silicone implant was not observed, a very mild foreign body reaction occurred around the implant. The patient is currently in remission. Our findings suggest that silicone implants are suitable for TP-I due to their remarkable affinity for human tissue and the low risk of a tissue reaction.

Biocompatibility assessment of porous chitosan-Nafion and chitosan-PTFE composites in vivo.

Chitosan (CS) is widely used as a scaffold material in tissue engineering. The objective of this study was to test whether porous chitosan membrane (PCSM) coating for Nafion used in implantable sensor reduced fibrous capsule (FC) density and promoted superior vascularization compared with PCSM coating for polytetrafluoroethylene (PTFE). PCSM was fabricated with solvent casting/particulate leaching method using silica gel as porogen and characterized in vitro. Then, PCSM-Nafion and PCSM-PTFE composites were assembled with hydrated PCSM and implanted subcutaneously in rats. The histological analysis was performed in comparison with Nafion and PTFE. Implants were explanted 35, 65, and 100 days after the implantation. Histological assessments indicated that both composites achieved presumed effects of porous coatings on decreasing collagen deposition and promoting angiogenesis. PCSM-PTFE exerted higher collagen deposition by area ratio, both within and outside, compared with that of PCSM-Nafion. Angiogenesis within and outside the PCSM-Nafion both increased over time, but that of the PCSM-PTFE within decreased.

Open inguinal hernia repair with the use of polyglycolic acid/trimethylene carbonate mesh: gross and pathologic assessment of the inguinal area at reoperation for recurrence.

PURPOSE: Our group tried to test the hypothesis of using a totally absorbable material for open inguinal hernia repair. However, the increased incidence of recurrences alleviated our initial enthusiasm regarding the technique. The purpose of the present study was to attain both gross and microscopic data that could at least in part justify the hernia repair failure from a patient included in our initial pilot study and was re-operated for recurrence. METHODS: A 65-year-old male patient was diagnosed clinically with a recurrence 24 months after open inguinal hernia repair with the use of polyglycolic acid/trimethylene carbonate mesh. The patient was operated for the recurrence upon our group on July 2012. The gross appearance of the inguinal area as well as the degree of chronic inflammation provoked by the used mesh as depicted by the pathologic analysis of specimens obtained intraoperatively were assessed. RESULTS: An open tension-free repair with the use of a non-absorbable mesh under spinal anesthetic was undertaken. Intraoperatively, after the division of the external oblique aponeurosis, only minor fibrotic reaction was observed a finding that was additionally confirmed pathologically. CONCLUSION: Polyglycolic acid/trimethylene carbonate mesh used for inguinal hernia repair was associated with a minimal inflammatory host reaction in the inguinal area at 3 years verified both grossly and microscopically.

Breast capsulectomy specimens and their clinical implications.

BACKGROUND: Plastic surgeons routinely submit breast capsulectomy surgical specimens for pathologic evaluation. However, clinically significant findings are rarely identified. In an effort to reduce health care costs and the unnecessary use of hospital resources, this study reviews the efficacy of submitting breast capsulectomy specimens for pathologic examination. METHODS: All patients from The Methodist Hospital in Houston, Texas, during the years 2000 to 2008 who underwent breast capsulectomy were selected for by Current Procedural Terminology codes 19370 and 19371 (open periprosthetic capsulotomy and periprosthetic capsulectomy of the breast, respectively). A total of 264 patients qualified for the study, and their pathology reports were reviewed. RESULTS: The pathology reports of 434 capsulectomy specimens in 264 patients revealed benign capsules in 206 patients (78.0 percent). Additional findings, including inflammation, calcification, granuloma, and necrosis, were identified in an additional 57 patients (21.6 percent). One patient (0.4 percent) had carcinoma identified within a breast capsule. This was a patient known preoperatively to have recurrent invasive ductal carcinoma that extended into the surrounding capsule. Therefore, none of the 264 capsulectomy specimens revealed new neoplasms, occult disease, or other clinically significant findings that changed the patient's postoperative treatment. CONCLUSIONS: No clinically significant findings were identified in this review of breast capsulectomy specimens in 264 patients. However, the cost for such pathologic examinations was substantial. In an effort to reduce health costs and the unnecessary use of hospital resources, breast capsulectomy specimens may not necessarily need to be routinely submitted for surgical pathologic evaluation.

In vivo biocompatibility assessment of (PTFE-PVDF-PP) terpolymer-based membrane with potential application for glaucoma treatment.

The aim of the work was to evaluate the in vivo biological behaviour of polymeric membrane materials for glaucoma implants. The base material was biostable synthetic terpolymer (PTFE-PVDF-PP) with proved biocompability (PN-EN ISO 10993). The samples manufactured in the form a membrane were subjected to chemical and physical treatment to create an open pore system within the polymer matrix. As a porogenic phase biodegradable natrium alginate in a fibrous form was employed. The non-perforating deep sclerectomy technique was performed in a rabbit model. The clinical observations were made after 14 and 30 days. During the study clinical symptoms of a moderate degree were observed, and histopathological changes were typical for foreign body implantation. At the end stage of the study no significant difference in histopathological assessment was found between control and experimental group. Similarities observed in both groups and relatively mild histopathological changes in the tissue surrounding the implant indicate that the observed symptoms come from a deep scleral trauma caused by surgery, and not by the presence of the implant itself.

Tissue reaction to new scalp clips.

Animal testing was used to observe skin reaction to plastic hair clips. The results were similar to the reaction caused by standard Raney scalp clips, indicating that this hair clip may be a useful local alternative to imported scalp clips. Clinical trials confirmed the safety of this type of clip in a series of craniotomy procedures.

Assessment of biocompatibility of chronically implanted polyimide and platinum intrafascicular electrodes.

Longitudinal intrafascicular electrodes (LIFEs) are electrodes designed to be placed inside the peripheral nerve to improve stimulation selectivity and to increase the recording signal-to-noise ratio. We evaluated the functional and morphological effects of either Pt wire LIFEs or polyimide-based thin-film LIFEs implanted in the rat sciatic nerve for 3 mo. The newly designed thin-film LIFEs are more flexible, can be micromachined and allow placement of more active electrode sites than conventional Pt LIFEs. Functional results at 1 mo indicated an initial decline in the nerve conduction velocity and in the amplitude of muscle responses, which recovered during the following 2 mo towards normal values. Morphological results showed that both types of LIFEs induced a mild scar response and a focal but chronic inflammatory reaction, which were limited to a small area around the electrode placed in the nerve. Both types of LIFEs can be considered biocompatible and cause reversible, minimal nerve damage.

In vitro assessment of the biological response to nano-sized hydroxyapatite.

Nano-sized, rod-like hydroxyapatite (nHA) crystals were produced and shown to be phasepure by X-ray diffraction analysis, as no secondary phases were observed. The nHA suspension was electrosprayed onto glass substrates using a novel processing routine to maintain nanocrystals of hydroxyapatite. The biocompatibility of nHAwas determined using human monocyte-derived macrophages and human osteoblast-like (HOB) cell models. The release of lactate dehydrogenase (LDH) from human monocyte-derived macrophages was measured as an indicator of cytotoxicity. The release of the inflammatory cytokine, tumour necrosis factor alpha (TNF-alpha) from cells in the presence of nHA crystallites was used as a measure of the inflammatory response. Although there was some evidence of LDH release from human monocyte-derived macrophages when in contact with high concentrations of nHA crystals, there was no significant release of TNF-alpha. Moreover, nHA-sprayed substrates were able to support the attachment and the growth of HOB cells. These results indicate that nHA crystals may be suitable for intraosseous implantation and offers the potential to formulate enhanced composites for biomedical applications.

In vitro host response assessment of biomaterials for cardiovascular stent manufacture.

The deployment of a vascular stent during angioplasty has greatly reduced the risks of restenosis. However, the presence of the device still induces a host response as well as a mechanical action on the blood vessel wall and an alteration of the haemodynamics. Platelet and inflammatory cells can adhere on the stent surface and be activated to produce biochemical signals able to stimulate an excessive proliferation of the smooth muscle cells with the consequent obstruction of the vessel lumen. For these reasons, the host response to two of the materials used in stent manufacture, stainless steel and diamond-like carbon, was investigated in vitro. The data showed that stainless steel induced a higher level of host response both in terms of platelet aggregation and macrophage activation. However, the spreading of inflammatory cells was more accentuated on diamond-like carbon. The inflammatory cells produced levels of platelet-derived growth factor, a key signal in smooth muscle cell proliferation, similar to stainless steel thus suggesting that carbon coatings may not be able to prevent restenosis.

Histological assessment of fifty breast capsules from smooth and textured augmentation and reconstruction mammoplasty prostheses with emphasis on the role of synovial metaplasia.

Fifty breast capsules surrounding smooth and textured breast prostheses were reviewed histologically, immunohistochemically, and ultrastructurally, and findings correlated with patient data. The histology of the capsules varied; although most consisted of a simple fibrocollagenous membrane, some were lined by organized, round to polyhedral cells similar to synovium. Histologically, the lining of the synovial type consisted of epithelioid cells overlying parallel bands of collagen, with basally located nuclei and cytoplasmic processes directed toward the surface and arranged within a well developed reticulin network. Immunohistochemically, the cells were vimentin positive, weakly positive focally for alpha-1-antitrypsin, alpha-antichymotrypsin, and lysozyme, and negative for EMA and AE1/AE3. Scanning electron photomicrographs showed a bosselated luminal lining overlying parallel bands of collagen. By transmission electron microscopy, both secretory and phagocytic cells could be distinguished. Some of the former were multinucleated. No basement membrane material could be identified, and cell junctions were rare. Histologically, immunohistochemically, and ultrastructurally the lining appeared identical to synovium and to the synovial metaplasia that has been described in sutured skin, after repeated subcutaneous injections of air, the bone-cement interface of loose hip prostheses and adjacent to gliding silastic tendon reconstruction rods. The physical and chemical composition of the prostheses, the mechanical forces, and the developmental response of the host mesenchymal tissue are thought to influence the formation and maintenance of the synovial metaplasia of the breast capsule.

Comparison of hemp and cotton fiber implants in muscle rat tissue. Study of the inflammatory response.

Hemp fiber is obtained from the plant Musa textilis. The cost of preparation of its raw fibers is low. The purpose of this paper was to compare the inflammatory response in the rat muscle tissue originated by both hemp and cotton fibers. Both types of fibers, were implanted in gluteal muscles of Sprague Dawley rats. The rats were sacrificed at 15, 30 and 60 postoperative days. Muscle tissue sections were stained with hematoxilyneosin. The inflammatory response was measured by subtracting the suture surface area from the total granulomatous area. At 15 days, the inflammatory response was more conspicuous for hemp than for cotton fiber (P < 0.05). At 30 and 60 days, responses were similar (P > 0.05). We cannot conclude that the hemp fiber is superior to cotton, nevertheless, they behave the same. Therefore, hemp constitutes an alternative as suture material.

Assessment of tissue reaction at suture knots; an adaptation of Sewell's scoring system.

From a theoretical point of view and from reported animal work the knot side should be considered the most relevant part of the suture loop for studying inflammatory foreign body reaction. In the present study a semi-quantitative histological assessment of inflammatory tissue reaction around the knots of implanted sutures is presented. To test the reliability of this method an animal model was used in which two suture materials with well-known differences in tissue reactivity were studied. Differences in tissue response around the knots between these materials proved to be highly significant statistically (tissue reactivity score (TRS) 44.17 vs. 58.71: p less than 0.001). No differences in TRS could be demonstrated between different localizations in the anterior abdominal wall of male Wistar rats. Implications of these findings with respect to future studies are discussed.

[Preparation of hip joint endoprostheses for qualitative and quantitative morphologic assessment]. / Präparation von Hüftgelenksendoprothesen zur qualitativen und quantitativen morphologischen Auswertung.

The morphological investigation of endoprostheses and the evaluation of the reaction with the surrounding bone tissue require the use of new preparation techniques. A standardized procedure of preparation is suggested to enable a comparison among various study groups. After removing the specimens (at autopsy), x-rays are taken, followed by separation into horizontal and longitudinal sections. These sections are undecalcified embedded retaining the implant/bone interface and grounded to thickness of 5-10 mu. First results of a quantitative analysis of bone loss are presented.

[2-phase embedding in the histologic assessment of complete uncemented synthetic acetabuli]. / Eine Zweiphaseneinbettung zur histologischen Darstellung ganzer unzementierter Hüftpfannen aus Kunststoff.

We describe a dual phase embedding method employing a routinely used methylmethacrylate mixture with a commercially available resin. Combination of both embedding materials provides fast and complete tissue penetration as well as the necessary hardness and stability for the consecutive grinding procedure.

A histologic assessment of canine anterior cruciate substitution with bovine xenograft.

Glutaraldehyde cross-linked bovine xenograft anterior cruciate ligament replacement has been investigated in dogs. The implants were functional for the activities of the dogs at one year of follow-up study. The knees were stable, and the articular surfaces on gross inspection showed only minimal evidence of degenerative changes. Histologic evaluation of the implants demonstrated a progressive ingrowth of the xenograft by host tissues. The host tissues grew parallel to the collagen scaffolding of the graft and consisted of host blood vessels and fibroblastic elements that produced collagen of host origin. The host response was benign in appearance without cellular evidence of rejection phenomena.

Assessment of tissue reactions to biomaterials: a model system using the foreign body response in the mouse lung to intravenously injected divinyl copolymer beads.

We have developed a reproducible model of granuloma formation in the mouse lung using a narrow size range (45-53 micron) of divinyl benzene copolymer beads as a standard test material. Approximately 10,000 beads are given by intravenous injection into the tail veins of mice whence they embolize to the lung and incite granuloma formation. This delivery system eliminates the superimposed inflammatory reaction due to trauma that occurs when materials are directly implanted at the test site by surgical incision. Granuloma size was quantitated at intervals from 3 h to 6 weeks by tracing mid-bead granuloma areas on the ground glass screen of a light microscope at a known magnification and measuring the areas with a digitizer interfaced with a microcomputer programmed to prepare histograms and to merge data from replicate experiments. At 3 h only a few polymorphonuclear leukocytes could be observed adhering to the beads. At 48 h, the time of maximum granuloma size (mean area = 7501 micron2), the granulomas consisted of both polymorphonuclear and mononuclear leukocytes. After 6 weeks, the granulomas were smaller, composed predominantly of mononuclear leukocytes and had a mean area of 2893 micron2. This model system allows the analysis of a large number of measurements, is reproducible, and provides a useful method for comparing the hosts' inflammatory response to a variety of potential biomaterials, as well as for determining the effectiveness of antiinflammatory drugs.

Tissue reactions to implanted dental amalgam, including assessment by energy dispersive x-ray micro-analysis.

Dental amalgam, either in the form of a solid rod or as a fine powder was implanted subcutaneously into guinea-pigs and the tissue reactions were examined after varying time periods. The solid rods were enclosed by fibrous capsules within which only extremely limited breakdown occurred. This appears to result from electrolytic corrosion of the gamma 2 (SnHg) phase of the rod's surface. Powdered amalgam induced granulomata and most of the particles of amalgam were actively digested by macrophages and giant cells. This resulted in the progressive loss of mercury and tin from the lesion and the formation of minute particles containing silver and sulphur which became widely distributed throughout the lesion, being associated with basal lamina, collagen and elastic tissue and giving rise to the formation of a tattoo. In contrast, some particles of amalgam, too large to be interiorised, were encapsulated by collagen and persisted almost unchanged. Intracellular small amalgam particles and aggregates of fine particles, resulting from their degradation, were seen within lymph node macrophages. It is extremely likely that the sequence of events leadng to the formation of an amalgam tattoo of the oral mucosa in Man are the same.