1、Designation: F 2451 05Standard Guide forin vivo Assessment of Implantable Devices Intended toRepair or Regenerate Articular Cartilage1This standard is issued under the fixed designation F 2451; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers general guidelines for the in vivoassessment of implantable devices intended
3、 to repair or regen-erate articular cartilage. Devices included in this guide may becomposed of natural or synthetic biomaterials (biocompatibleand biodegradable) or composites thereof and may containcells or biologically active agents such as growth factors,synthetic peptides, plasmids, or cDNA.1.2
4、 Guidelines include a description and rationale of variousanimal models utilizing a range of species such as rabbit(lupine), dog (canine), pig (porcine), goat (caprine), sheep(ovine), and horse (equine). Outcome measures based onhistologic, biochemical, and mechanical analyses are brieflydescribed a
5、nd referenced. The user should refer to specific testmethods for additional detail.1.3 This guide is not intended to include the testing of rawmaterials, preparation of biomaterials, sterilization, or packag-ing of product.ASTM standards for these steps are available inReference Documents.1.4 The va
6、lues stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bil
7、ity of regulatory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2F 561 Practice for the Retrieval and Analysis of ImplantedMedical Devices, and Associated TissuesF 565 Practice for Care and Handling of Orthopedic Im-plants and InstrumentsF 895 Test Method for Agar Diffusion Cel
8、l Culture Screen-ing for CytotoxicityF 981 Practice for Assessment of Compatibility of Bioma-terials for Surgical Implants with Respect to Effect ofMaterials on Muscle and BoneF 1983 Practice for Assessment of Compatibiltiy ofAbsorbable/Resorbable Biomaterials for Implant Applica-tionsF 2150 Guide f
9、or Characterization and Testing of Biomate-rial Scaffolds Used in Tissue-Engineered Medical Products2.2 Other Documents:ISO-10993 Biological Evaluation of Medical DevicesPart 5: Tests for in vitro Cytotoxicity321 CFR Part 58 Good Laboratory Practice for NonclinicalLaboratory Studies43. Terminology3.
10、1 Definitions:3.1.1 cartilage regenerationthe formation of articular-like cartilage that has histologic, biochemical, and mechanicalproperties similar to that of native articular cartilage (1, 2).53.1.2 cartilage repairthe process of healing injured carti-lage or its replacement through cell prolife
11、ration and synthesisof new extracellular matrix (1, 2).3.1.3 compact boneclassification of ossified boney con-nective tissue characterized by the presence of osteons con-taining lamellar bone.3.1.4 femoral condylesthe anatomic site corresponding tothe distal end of the femur characterized by medial
12、and lateralconvex surfaces that are lined by cartilage and articulate withthe proximal tibia and medial and lateral menisci.3.1.5 fibrocartilagedisorganized cartilagenous tissue hav-ing an abnormally high content of type I collagen.3.1.6 growth platethe anatomic location within the epi-physeal regio
13、n of long bones corresponding to the site of1This guide is under the jurisdiction of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.44 on Assessment for TEMPs.Current edition approved April 1, 2005. Published May 2005.2For referenc
14、ed ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd S
15、t.,4th Floor, New York, NY 10036.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.5The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100
16、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.growth of bone through endochondral bone formation. Thegrowth plate in skeletally mature animals is fused.3.1.7 hyaline articular cartilagecartilagenous connectivetissue located in diarthrodial joints and characterized
17、by itslocalization to articulating surfaces.3.1.8 marrowalso called myeloid tissue; soft, gelatinoustissue that fills the cavities of the bones. It is either red oryellow, depending upon the preponderance of vascular (red) orfatty (yellow) tissue.3.1.9 matrixa term applied to either the exogenous im
18、-planted scaffold or the endogenous extracelluar substance(otherwise known as extracellular matrix) derived from thehost.3.1.10 patellathe bone of the knee joint which articulateswithin the trochlear groove of the femur.3.1.11 residence timethe time at which an implantedmaterial (synthetic or natura
19、l) can no longer be detected in thehost tissue.3.1.12 skeletal maturitythe age at which the epiphysealplates are fused.3.1.13 subchondral platethe margin of compact bone indirect apposition to the articular cartilage.3.1.14 synovial fluidthe fluid secreted by synovium pro-viding lubrication and nutr
20、ition to the joint surfaces.3.1.15 synoviumthe epithelial lining of synovial jointcavities that produce synovial fluid.3.1.16 tidemarkthe anatomic site in articular cartilagecorresponding to the margin between cartilage and the under-lying calcified cartilage.3.1.17 trabecular boneclassification of
21、ossified boneyconnective tissue characterized by spicules surrounded bymarrow space.3.1.18 trochlear groovethe anatomic site on the distal endof the femur corresponding to the region of articulation withthe patella.4. Significance and Use4.1 This guide is aimed at providing a range of in vivomodels
22、to aid in preclinical research and development of tissueengineered medical products intended for the clinical repair orregeneration of articular cartilage.4.2 This guide includes a description of the animal models,surgical considerations, and tissue processing as well as thequalitative and quantitat
23、ive analysis of tissue specimens.4.3 The user is encouraged to utilize appropriate ASTM andother guidelines to conduct cytotoxicity and biocompatibilitytests on materials or devices, or both, prior to assessment of thein vivo models described herein.4.4 It is recommended that safety testing be in ac
24、cordancewith the provisions of the FDA Good Laboratory PracticesRegulations 21 CFR 58.4.5 Safety and Effectiveness studies to support IDE (Inves-tigational Device Exemption), PMA (Premarket Approval), or510K submissions should conform to appropriate FDA guide-lines for development of medical devices
25、.4.6 Animal model outcomes are not necessarily predictiveof human results and should, therefore, be interpreted cau-tiously with respect to potential applicability to human condi-tions.5. Animal ModelsNOTE 1This section provides a description of the options to considerin determining the appropriate
26、animal model and cartilage defect size andlocation.5.1 Joint Size and Load:5.1.1 A high proportion of hyaline cartilage injuries inhumans occur in the knee joint predominantly in the medialcompartment (that is, medial femoral condyle and tibial pla-teau). Accordingly, the knee joint is commonly used
27、 forassessing cartilage repair/regeneration in animal models.5.1.2 The knee is a complex diarthrodial joint involvingprimarily two separate articulations; femoropatellar and femo-rotibial. The articular surfaces of the distal femur and proximaltibia are incongruent and contain wedge shaped fibrocart
28、ilag-enous menisci separating the articular surfaces. Contact be-tween the cartilage of the femoral condyles and that of thetibial plateau occurs at the innermost central region of eachmedial and lateral meniscus. Mechanical load is distributeddirectly from the femur to the tibia as well as indirect
29、ly throughthe menisci. The patella articulates with the femoral condylewithin the trochlear groove.5.1.3 Significant variability exists between animal specieswith respect to the weight of the animal, joint anatomy, and gaitthereby influencing joint kinetics, range of motion, and me-chanical forces o
30、n joint surfaces. These factors influence thethickness and distribution of articular cartilage within the jointsas well as macromolecular content, distribution, and collagenarchitecture. These factors play a significant role in theresponse to injury or disease of articular cartilage (see Table 1).Th
31、e user should consider carefully the animal model that isappropriate for the stage of investigation of an implanteddevice (3).TABLE 1 Animal Models for the Assessment of Cartilage RepairSpeciesBreedCommonly UsedAge ofAdult EqivalancyWeight atAdult EquivalancyDefect SitesCommonly UsedCartilage Thickn
32、essat FemoralCondyle (mm)CriticalSize Defect(Diameterin mm)RabbitA(Lupus or Lupine) New Zealand White 9 months 34 kg FC, TG, TP, P 0.250.75 3DogB(Canine) Mongrel, Beagle 12 years 1530 kg FC, TG, P 1.3 PigB(Porcine) Minipig 10 months1 year2040 kg FC, TG GoatB(Caprine) Spanish, Dairy, Boer Cross 23 ye
33、ars 4070 kg FC, TG, TP, P 1.52 SheepB(Ovine) Suffolk or Texel 23 years 3580 kg FC, TG 1.7 7HorseB(Equine) Mixed, Thoroughbred, Quarter Horse 24 years 400500 kg FC, TG, RC 23 9Asmall animal.Blarge animal; FC, femoral condyle; TG, trochlear groove; TP, tibial plateau; P, Patella; RC, radial carpal.F24
34、510525.1.4 Mechanical load has been shown to affect cartilagerepair.Amongst the mechanobiological factors, the intermittenthydrostatic pressure and shear stresses play an important rolein modulating cartilage development, and maintenance as wellas cartilage degeneration (4, 5). The impact of mechani
35、cal loadextent or duration on the implanted device, surrounding nativearticular cartilage, and underlying bone varies depending onthe anatomic site and the position of the joint (6). The defectsite chosen to evaluate implants should, therefore, factor theimpact of mechanical load on the performance
36、of the implant.5.1.5 It is suggested that the gait and stance of a particularspecies be considered when factoring the extent of exposure ofthe implant site to stress during standing and motion.5.1.6 The extent of compressive and shear forces in thefemoral condyles, trochlear groove, and tibial plate
37、au differsignificantly as do differing anatomic sites of the same articularsurface.5.1.7 It is recommended that an appropriate species andanatomic site be chosen having articular surfaces and thicknesssufficiently large to adequately investigate and optimize theformulation, design, dimensions, and a
38、ssociated instrumenta-tion envisaged for human use.5.1.8 Larger animals are more appropriate for studyingrepair in joints that have greater articular cartilage surface areasand a thickness that more closely approximates that of humans.5.1.9 Larger defect dimensions generally require a methodof fixat
39、ion to secure the implant and thereby reduce implantdislocation. The method of implant immobilization can nega-tively impact both the surrounding host tissue and repair tissue.Accordingly, the difference in the design of the test device insmall animals which generally do not require fixation should
40、befactored into the interpretation of results with respect topredictability of outcomes in larger animal models and humansrequiring fixation.5.1.10 For each species, a critical size defect is defined asthe minimum defect dimension (in diameter) that the animal isincapable of repairing without interv
41、ention. The diameter ofcritical defects generally differ for each species and should beconsidered carefully when designing the implant dimensionsand method of fixation.5.2 Handling:5.2.1 Exposure of implants to extreme and highly variablemechanical forces as a result of jumping, running, hyperexten-
42、sion, or hyperflexion of the joint can lead to increasedvariability in outcome measures.5.2.2 Care should be used to reduce stress or other factorsthat cause behaviors associated with rapid or extreme, or both,movements of joints.5.3 Gender:5.3.1 Due to the impact of circulating steroids on cartilag
43、eand bone metabolism and regeneration, the choice of gendershould be considered. Animals in lactation should not be used.5.3.2 It is recommended that the gender be the same withinthe cohort.5.4 Age:5.4.1 Bone and cartilage undergo dynamic changes in me-tabolism and remodeling during growth. Due to t
44、he impact ofthese physiologic processes on tissue repair, the age of aparticular species should be chosen to exceed the age ofskeletal maturity. The cohorts should have fused epiphysealgrowth plates. Skeletal maturity varies between species andcan be generally determined radiographically if necessar
45、y.5.4.2 Older animals have a higher propensity for osteopeniaand degenerative joint diseases such as osteoarthritis, and havea decreased capacity to repair articular cartilage defects. Ifspecific conditions are considered important for the intendeddevice assessment, then an appropriate model should
46、be used.5.4.3 The mesenchymal stem cell pool, growth factor re-sponsiveness, and metabolic activity of cells generally de-creases with age (7). Thus, reparative processes that aredependent on the number and activity of native cells may bepartially compromised in older animals.5.5 Study Duration:5.5.
47、1 The length of the study depends on the stage of devicedevelopment, the species used, the size of the defect, andcomposition and design of implant.5.5.2 In small animals, small defects implanted for 6 to 8weeks provide information regarding residence time of implantand fixation device as well as th
48、e type of repair.5.5.3 Using larger animals, study periods of 8 to 12 weeksare limited to providing information regarding the biocompat-ibility, early cellular responsiveness, and the persistence andcondition of the implant within the defect.5.5.4 Periods of 6 to 12 months are generally necessary to
49、gain confidence in the extent of success in the repair orregeneration of articular cartilage based on histologic andbiochemical outcome measures, including the interface withadjacent cartilage and subchondral bone, as well as theopposing articular surface.5.6 Rabbit ModelThe femoral condyle and trochleargroove are most frequently used as sites for evaluation ofimplants in rabbits (8-14). The use of the patella has beeninvestigated as well (15, 16).5.6.1 The use of rabbits is generally more economicalcompared to larger species.5.6.2 Due to the smal
