Current considerations in medical device pathology

Alves, Antoine; Wancket, Lyn M.; Metz, Alan

doi:10.1016/b978-0-08-102643-4.00020-3

Cited by 5 publications

(5 citation statements)

References 61 publications

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“…The scaffolds were then left to continue degrading until week 12 and were observed to lose their integrity during handling. As such no measurement was possible at this stage, thus establishing that this representative high-strength scaffold can induce osteotransduction within the desired timeframe [ 34 , 39 , 107 ]. This degradation period corresponds to a report by Turnbull et al (2017) documenting that a porous ß-dicalcium silicate (ß-Ca2SiO4) scaffold was aimed at bone healing applications [ 108 ].…”

Section: Resultsmentioning

confidence: 99%

“…The scaffold biodegradation profile plays an essential role in releasing a loaded drug through customising these scaffolds to degrade at a similar rate to the bone ingrowth, where the newly formed bone gradually replaces the scaffolds in an osteotransductive manner, thus obtaining a suitable drug release mechanism [ 5 , 34 , 35 ]. Since chitosan (CS) can undergo enzymatic degradation in vivo due to its degradable glycosidic chains and the degradation products can be digested naturally after entering the bodies’ metabolic cycle, a plethora of studies have been carried out in fabricating bone scaffolds involving this biopolymer [ 17 , 36 , 37 , 38 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

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Bioresorbable Chitosan-Based Bone Regeneration Scaffold Using Various Bioceramics and the Alteration of Photoinitiator Concentration in an Extended UV Photocrosslinking Reaction

Azaman

Zhou

Blanes-Martínez

et al. 2022

Gels

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Bone tissue engineering (BTE) is an ongoing field of research based on clinical needs to treat delayed and non-union long bone fractures. An ideal tissue engineering scaffold should have a biodegradability property matching the rate of new bone turnover, be non-toxic, have good mechanical properties, and mimic the natural extracellular matrix to induce bone regeneration. In this study, biodegradable chitosan (CS) scaffolds were prepared with combinations of bioactive ceramics, namely hydroxyapatite (HAp), tricalcium phosphate-α (TCP- α), and fluorapatite (FAp), with a fixed concentration of benzophenone photoinitiator (50 µL of 0.1% (w/v)) and crosslinked using a UV curing system. The efficacy of the one-step crosslinking reaction was assessed using swelling and compression testing, SEM and FTIR analysis, and biodegradation studies in simulated body fluid. Results indicate that the scaffolds had comparable mechanical properties, which were: 13.69 ± 1.06 (CS/HAp), 12.82 ± 4.10 (CS/TCP-α), 13.87 ± 2.9 (CS/HAp/TCP-α), and 15.55 ± 0.56 (CS/FAp). Consequently, various benzophenone concentrations were added to CS/HAp formulations to determine their effect on the degradation rate. Based on the mechanical properties and degradation profile of CS/HAp, it was found that 5 µL of 0.1% (w/v) benzophenone resulted in the highest degradation rate at eight weeks (54.48% degraded), while maintaining compressive strength between (4.04 ± 1.49 to 10.17 ± 4.78 MPa) during degradation testing. These results indicate that incorporating bioceramics with a suitable photoinitiator concentration can tailor the biodegradability and load-bearing capacity of the scaffolds.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bioresorbable Chitosan-Based Bone Regeneration Scaffold Using Various Bioceramics and the Alteration of Photoinitiator Concentration in an Extended UV Photocrosslinking Reaction

Azaman

Zhou

Blanes-Martínez

et al. 2022

Gels

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“…The fluorochrome labels work by chelating the mineralised front during the bone mineralisation process at the time of injection, which enables the evaluation of the dynamic bone formation by measuring the distance between fluorochromes labels [ 42 ]. It has also been documented that fluorochrome labelling can be used to evaluate the bone mineralisation rate, remodelling, and the signs of toxicity in implants on the bone in vivo [ 14 ].…”

Section: Resultsmentioning

confidence: 99%

“…The fabricated biodegradable scaffold will release growth factors while degrading and then be secreted from the body naturally after it completes its function. Therefore, an ideal scaffold should be able to degrade in a gradational way for an expected period in order to be replaced by newly formed bone tissue from the bonded cells, known as the osteotransduction process [ 14 ]. This degradation will result in the breakdown of the scaffold and the resorption of the protein, such as bone morphogenetic protein-2 (BMP-2), incorporated in the scaffold to the targeted location.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Scaffold In Vivo Biodegradability for Bone Regeneration Using P28 Peptide Formulations

Azaman

Fournet²,

Hamid

et al. 2023

Pharmaceuticals

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The field of bone tissue engineering has shown a great variety of bone graft substitute materials under development to date, with the aim to reconstruct new bone tissue while maintaining characteristics close to the native bone. Currently, insufficient scaffold degradation remains the critical limitation for the success of tailoring the bone formation turnover rate. This study examines novel scaffold formulations to improve the degradation rate in vivo, utilising chitosan (CS), hydroxyapatite (HAp) and fluorapatite (FAp) at different ratios. Previously, the P28 peptide was reported to present similar, if not better performance in new bone production to its native protein, bone morphogenetic protein-2 (BMP-2), in promoting osteogenesis in vivo. Therefore, various P28 concentrations were incorporated into the CS/HAp/FAp scaffolds for implantation in vivo. H&E staining shows minimal scaffold traces in most of the defects induced after eight weeks, showing the enhanced biodegradability of the scaffolds in vivo. The HE stain highlighted the thickened periosteum indicating a new bone formation in the scaffolds, where CS/HAp/FAp/P28 75 µg and CS/HAp/FAp/P28 150 µg showed the cortical and trabecular thickening. CS/HAp/FAp 1:1 P28 150 µg scaffolds showed a higher intensity of calcein green label with the absence of xylenol orange label, which indicates that mineralisation and remodelling was not ongoing four days prior to sacrifice. Conversely, double labelling was observed in the CS/HAp/FAp 1:1 P28 25 µg and CS/HAp/FAp/P28 75 µg, which indicates continued mineralisation at days ten and four prior to sacrifice. Based on the HE and fluorochrome label, CS/HAp/FAp 1:1 with P28 peptides presented a consistent positive osteoinduction following the implantation in the femoral condyle defects. These results show the ability of this tailored formulation to improve the scaffold degradation for bone regeneration and present a cost-effective alternative to BMP-2.

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“…The study pathologist should familiarize themselves with the content of applicable guidance documents and standards. 3,5 This potentially includes the entire ISO 10993 standard series, but particularly ISO 10993-6:2016 (for local toxicity and tolerability), 4 ISO 10993-11:2017 (for systemic toxicity) 17 (discussed in Alves, 2019), 18 ISO 10993-1:2018 (for developing the comprehensive risk assessment approach), 6 and FDA usage guidance for ISO 10993-1. 7 In addition, relevant (vertical) ISO standards other than series 10993 and other related (lateral) international regulatory documents, when relevant, may be consulted for evaluations of cardiovascular, eye, and dental implants (reviewed by Schuh and Funk 19 and Drevon-Gaillot 20 ).…”

Section: Considerations For Medical Device Implant Site Evaluationmentioning

confidence: 99%

Scientific and Regulatory Policy Committee Points to Consider for Medical Device Implant Site Evaluation in Nonclinical Studies

O'Brien

Schuh²,

Wancket

et al. 2022

Toxicol Pathol

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Nonclinical implantation studies are a common and often critical step for medical device safety assessment in the bench-to-market pathway. Nonclinical implanted medical devices or drug-device combination products require complex macroscopic and microscopic pathology evaluations due to the physical presence of the device itself and unique tissue responses to device materials. The Medical Device Implant Site Evaluation working group of the Society of Toxicologic Pathology’s (STP) Scientific and Regulatory Policy Committee (SRPC) was tasked with reviewing scientific, technical, and regulatory considerations for these studies. Implant site evaluations require highly specialized methods and analytical schemes that should be designed on a case-by-case basis to address specific study objectives. Existing STP best practice recommendations can serve as a framework when performing nonclinical studies under Good Laboratory Practices and help mitigate limitations in standards and guidances for implant evaluations (e.g., those from the International Organization for Standardization [ISO], ASTM International). This article integrates standards referenced by sponsors and regulatory bodies with practical pathology evaluation methods for implantable medical devices and combination products. The goal is to ensure the maximum accuracy and scientific relevance of pathology data acquired during a medical device or combination drug-device implantation study.

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Current considerations in medical device pathology

Cited by 5 publications

References 61 publications

Bioresorbable Chitosan-Based Bone Regeneration Scaffold Using Various Bioceramics and the Alteration of Photoinitiator Concentration in an Extended UV Photocrosslinking Reaction

Bioresorbable Chitosan-Based Bone Regeneration Scaffold Using Various Bioceramics and the Alteration of Photoinitiator Concentration in an Extended UV Photocrosslinking Reaction

Enhancement of Scaffold In Vivo Biodegradability for Bone Regeneration Using P28 Peptide Formulations

Scientific and Regulatory Policy Committee Points to Consider for Medical Device Implant Site Evaluation in Nonclinical Studies

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