Alginate Microencapsulation Technology

RESEARCH

Alginate Microencapsulation Technology for the Percutaneous
Delivery of Adipose-Derived Stem Cells
Hunter R. Moyer, MD,* Ramsey C. Kinney, MD, PhD,† Kimberly A. Singh, MD,* Joseph K. Williams, MD,*‡
Zvi Schwartz, DMD, PhD,‡ and Barbara D. Boyan, PhD‡

Background: Autologous fat is the ideal soft-tissue filler; however, its
widespread application is limited because of variableclinical results and poor
survival. Engineered fillers have the potential to maximize survival. Alginate
is a hydrogel copolymer that can be engineered into spheres of 200 m,
thus facilitating mass transfer, allowing for subcutaneous injection, and
protecting cells from shearing forces.
Methods: Alginate powder was dissolved in saline, and adipose-derived
stem cells (ADSCs) were encapsulated(1 million cells/mL) in alginate using
an electrostatic bead generator. To assess effects of injection on cell viability,
microspheres containing ADSCs were separated into 2 groups: the control
group was decanted into culture wells and the injection group was mixed
with basal media and injected through a 21-gauge needle into culture wells.
Microbeads were cultured for 3 weeks, and cell numberand viability were
measured weekly using electron and confocal microscopy. To assess effects
of percutaneous injection in vivo, twenty-four male nude mice were randomly separated into 2 groups and injected with either empty microcapsules
or ADSC-laden microcapsules. Mice were harvested at 1 and 3 months, and
the implants were examined microscopically to assess bead and cell viability.Results: A flow rate of 5 mL/h and an electrostatic potential of 7 kV
produced viable ADSC-laden microbeads of 200 m. There were no
differences in bead morphology and ADSC viability between microcapsules
placed versus injected into tissue culture plates for up to 3 weeks. Microspheres implanted in a nude mouse model show durability up to 3 months
with a host response around each individual sphere.ADSCs remained viable
and showed signs of mitosis.
Conclusions: ADSCs can be readily cultured, encapsulated, and injected in
alginate microspheres. Stem cells suspended in alginate microspheres survive in vivo and are seen to replicate in vitro.
Key Words: alginate microbeads, injectable, adipose stem cells
(Ann Plast Surg 2010;XX: 00)

I

njectable tissue fillers are in high demandbecause there is no
downtime, results are immediate, and injecting is both safe and
cost-effective. Hyaluronic acid, polymethyl methacrylate spheres,
and hydroxyapatite beads have become popular because a permanent, autologous solution does not exist.1– 4 Autologous fat is the
ideal soft-tissue filler; it is readily available, easy to harvest, and

Received September 19, 2009, and accepted forpublication, after revision,
January 10, 2010.
From the *Division of Plastic and Reconstructive Surgery, Emory University,
Atlanta, GA; †Department of Orthopaedics, Atlanta Medical Center, Atlanta,
GA; ‡Children’s Healthcare of Atlanta, Atlanta, GA; and §Department of
Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA.
Supported by a grant from Children’s Healthcare ofAtlanta and the Department
of Defense, Wallace H. Coulter Translational/Clinical Research Seed Grant.
Originally presented in the Resident Competition of the 52nd Annual Meeting of
the Southeastern Society of Plastic and Reconstructive Surgeons in San Juan,
Puerto Rico.
Reprints: Hunter R. Moyer, MD, Department of Surgery, Emory University, 1364
Clifton Road, Atlanta, GA 30322. E-mail:hmoyer@emory.edu.
Copyright © 2010 by Lippincott Williams & Wilkins
ISSN: 0148-7043/10/0000-0001
DOI: 10.1097/SAP.0b013e3181d37713

Annals of Plastic Surgery • Volume XX, Number XX, XXX 2010

safe. However, consistent results are lacking thereby inhibiting
widespread use.5–9 In addition, a recent survey of members of the
American Society of Esthetic Plastic Surgeons revealed that over
half of...