Biodegradable polymers: an update on drug delivery in bone and cartilage diseases

ABSTRACT

Introduction: The unique structure of bone and cartilage makes the systemic delivery of free drugs to those connective tissues very challenging. Consequently, effective and targeted delivery for bone and cartilage is of utmost importance. Engineered biodegradable polymers enable designing carriers for a targeted and temporal controlled release of one or more drugs in concentrations within the therapeutic range. Also, tissue engineering strategies can allow drug delivery to advantageously promote the in situ tissue repair.

Areas covered: This review article highlights various drug delivery systems (DDS) based on biodegradable biomaterials to treat bone and/or cartilage diseases. We will review their applications in osteoporosis, inflammatory arthritis (namely osteoarthritis and rheumatoid arthritis), cancer and bone and cartilage tissue engineering.

Expert opinion: The increased knowledge about biomaterials science and of the pathophysiology of diseases, biomarkers, and targets as well as the development of innovative tools has led to the design of high value-added DDS. However, some challenges persist and are mainly related to an appropriate residence time and a controlled and sustained release over a prolonged period of time of the therapeutic agents. Additionally, the poor prediction value of some preclinical animal models hinders the translation of many formulations into the clinical practice.

KEYWORDS:

• Bone diseases
• cartilage diseases
• biodegradable polymers
• drug delivery systems
• controlled drug release
• targeted drug delivery
• tissue engineering

Article highlights

• The treatment of bone and cartilage diseases remains an unmet medical need despite the efforts to develop effective and innovative strategies.

• Novel drugs (e.g. chemical substances and biological drugs), innovative tools (e.g. nanotechnology and 3D printing), and smart drug delivery devices (e.g. stimuli-responsive biomaterials) can lead to a revolution in the current available treatments.

• In addition to passive targeting, drug delivery systems can be advanced by their functionalization with targeting moieties specific for bone or cartilage tissues.

• Drug loading and releasing from tissue engineering approaches can modulate and enhance tissue repair.

• Clinical translation of promising treatments has been hindered mainly due to the poor correlation between pre-clinical and clinical results.

This box summarizes the key points contained in the article.

Acknowledgments

Authors acknowledge the financial support from FCT (Portuguese Foundation for Science and Technology) for the project PTDC/CTM-BIO/4388/2014 – SPARTAN, the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER) (NORTE-01-0145-FEDER-000023 FROnTHERA) and the NORTE 2020 Structured Project, cofunded by Norte2020 and Horizon 2020 by the contract number H2020-NMBP-PILOTS-2016 721062 Project Flexpol. Authors would also like to acknowledge FCT/MCTES (Ministry of Science, Technology and Higher Education) and the FSE/POCH (European Social Fund through the Operational Program of Human Capital), for the PhD scholarship PD/BD/11384/2015 of A. C. Lima (PD/59/2013).

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.