Injectable biomaterials biocompatibility

Mobnaro, G., Leroux, J. C., Damas, J. Adam, A. (2002) Biocompatibility of thermosensitive chitosan-based hydrogels an in vivo experimental approach to injectable biomaterials. Biomaterials, 23, 2717-22. 

The two most important areas of research when developing an injectable biomaterial for potential human use are (1) material characterization and (2) biocompatibility testing. Material characterization requires extensive rheological testing to assess a material s delivery performance and mechanical stability. The following lists summarize the general material characterization tests required by the FDA. 

The IDE submission is the cmcial hurdle and major milestone that transitions a promising material into a viable and testworthy medical device. The IDE s format is a testament to this transformation. The first half of the submission is a detailed report of the injectable biomaterial s evolution and optimization -including all background data and all reports of prior investigation. This section includes the history of the material, all current mechanical and chemical testing, in vitro and in vivo modeling, and biocompatibility results. The second half of the submission, however, focuses on the injectable biomaterial as a device. This... 

Caleium phosphate cements (CPCs) have been investigated extensively as injectable bone replacement biomaterials due to their similar chemical composition to the mineral component of bone. A Umitation of CPCs is their brittle mechanical properties and slow degradation in vivo Therefore, enhancing the mechanical properties, injectability, and rate of cellular infiltration and remodeling of CPCs while preserving their favorable biocompatibility is an important and active area of research. While ceramic biomaterials are discussed in greater detail in Chapter 2, the biocompatibihty of conventional CPCs, as well as the implications of recent advancements on the biocompatibility of these biomaterials, will be reviewed in this chapter. 

The extract dilution type of cell culture assay requires a solvent extraction of the biomaterial under consideration and testing of this extract, most commonly at various dilutions, for evidence of cytotoxicity and cellular interaction. This type of cell culture assay finds its most common use in providing information for regulatory compliance. As identified in the preceding Materials for Medical Devices section and in Table 1, low-molecular-weight extractables are of concern regarding biocompatibility. The extraction assay, carried out with a series of solvents that are hydrophilic and hydrophobic, permits examination of the potential cytotoxicity of extracts and the identification of materials within a biomaterial that may be cytotoxic. These types of assays ultimately permit identification and characterization of cytotoxic materials within biomaterials or the lack of cytotoxicity, as well as providing correlation with in vivo assays such as sensitization, irritation, intracutaneous (intradermal) reactivity, and other tests where the in vivo injection of extracts is required. 

De Souza, R., Zahedi, R, Allen, C.J., and Piquette-Miller, M. 2009. Biocompatibility of injectable chitosan-phospholipid implant systems. Biomaterials 30 3818-3824. 

Soft tissue responses to biomaterials for medical devices are generally viewed from the inflammation and wound healing perspectives and are usually considered as parts of the tissue or cellular host responses to injury. Placement of a biomaterial or medical device in the soft tissue environment involves injection, insertion, or surgical implantation, all of which injure the tissues or organs involved. Early host responses are dynamic and change with time (Table 2.1). It is important to consider this time variable in determining the host response or biocompatibility of a material. 

Mi F-L, Tan Y-C, Liang H-F, Sung H-W (2002) In vivo biocompatibility and degradability of a novel injectable-chitosan-based implant. Biomaterials 23(1) 181-191. doi 10.1016/S0142-... 

The assessment of the biocompatibility of biodegradable polymers takes into account the incidence of the inflammatory and healing responses of the injected and implanted biomaterials [58],... 

As was previously explained, the assessment of the biocompatibility of biodegradable polymers takes into account the incidence of the inflammatory and healing responses of the injected and implanted biomaterials [58]. Research has pointed out that PLGA delivery devices that contain different agents are biocompatible and do not exhibit undesirable reactions when used in therapeutic applications in vivo. 

Chiu YL, Chen SC, Su CJ et al (2009) pH-triggered injectable hydrogels prepared from aqueous N-palmitoyl chitosan in vitro characteristics and in vivo biocompatibility. Biomaterials 30 4877-4888... 

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