Cell encapsulation: technical and clinical advances

• Cell encapsulation involves immobilization of allogeneic or xenogeneic cells in a semipermeable but immunoprotective membrane.
• Cell encapsulation delivers biological products to patients without the need for immunosuppression.
• Synthetic molecules that can be reproducibly manufactured are preferable to natural polymers for capsule fabrication.
• Stricter requirements apply for xenografts than for allograft microencapsulation.
• Clinical trials are evaluating the use of encapsulated cells in various human diseases.

Treating many chronic diseases will require a tight, minute-to-minute regulation of therapeutic molecules that is currently not achievable with most pharmaceutical therapies. For these diseases, implantable living cellular systems may be able to provide unlimited drug delivery, enabling seamless matching of treatment duration with disease longevity. Cell encapsulation is an advanced technology that achieves this goal and represents a viable therapeutic option. The advanced state of the field has allowed researchers to inch forward into therapeutic domains previously untouchable because of the myriad disparate fields that intersect biomaterials and cells. Here, we discuss the next generation of clinical trials and potential approaches, ‘smart’ and responsive encapsulation systems, sophisticated and multifunctional devices, and novel imaging tools, together with the future challenges in the field.