Switching of Cell Proliferation/Differentiation in Thiol–Maleimide Clickable Microcapsules Triggered by in Situ Conjugation of Biomimetic Peptides

Abstract

Extracellular environments significantly affect cell proliferation, differentiation, and functions. The extracellular environment changes during many physiological and pathological processes such as embryo development, wound healing, and tumor growth. To mimic these changes, we developed novel thiol−maleimide clickable alginate microcapsules, which can introduce thiol-containing peptides by "in situ conjugation" with maleimide-modified alginate, even in serum-containing cell culture media. Additive peptides were rapidly concentrated into microcapsules by a diffusionreaction process in the capsule. The proliferation of encapsulated fibroblasts was accelerated by in situ conjugation of CRGDS, while free RGDS showed no effect. Moreover, encapsulated preosteoblastic cells started osteogenic differentiation via in situ conjugation of BMP-2 mimetic peptides such as CDWIVA and CG-BMP-2 knuckle epitope peptide, while BMP-2 did not induce differentiation of the encapsulated cells. Especially in tissue engineering, accurate and inexpensive methods for inducing cell differentiation are required. We believe that this in situ conjugation approach employing various functional peptides will be useful in biomedical, bioindustrial, and biochemical fields in the future.

Modulating Alginate Hydrogels for Improved Biological Performance as Cellular 3D Microenvironments

“…Guidance of MSC fate commitment into the osteogenic lineage has also been explored in alginate hydrogels integrating peptide sequences derived from bone morphogenic proteins (BMP). For example, BMP-2 derived peptides containing DWIVA and KIPKASSVPTELSAISTLYL (BMP-2 knuckle epitope, BMP-2 KE), have been conjugated to alginate (Madl et al, 2014 ; Oki et al, 2019 ). Madl et al ( 2014 ) modified alginate with peptides containing RGD and these two sequences, observing a significant increase in alkaline phosphatase (ALP) activity of osteoblasts entrapped within RGD/BMP-2 KE alginate hydrogels, but not significant differences in osteoblasts entrapped in RGD hydrogels or RGD/DWIVA hydrogels (Madl et al, 2014 ).…”

“…Oki et al ( 2019 ) produced an alginate derivative containing maleimide groups, which were able to react under physiological conditions with thiol-containing peptides (Oki et al, 2019 ). The authors explored this platform to switch cell proliferation and differentiation by encapsulating cells within maleimide-alginate microcapsules and then exposing them to the cell adhesive RGD peptide and the BMP-2 mimetic DWIVA and BMP-2 KE peptides 1 day after encapsulation (Oki et al, 2019 ). Efficient peptide coupling occurred, without affecting mechanical properties (Oki et al, 2019 ).…”

“…The authors explored this platform to switch cell proliferation and differentiation by encapsulating cells within maleimide-alginate microcapsules and then exposing them to the cell adhesive RGD peptide and the BMP-2 mimetic DWIVA and BMP-2 KE peptides 1 day after encapsulation (Oki et al, 2019 ). Efficient peptide coupling occurred, without affecting mechanical properties (Oki et al, 2019 ). On days following RGD coupling, fibroblasts proliferation significantly increased when compared to cells encapsulated within microcapsules where RGD was non-covalently bound or not present (Oki et al, 2019 ).…”

“…Efficient peptide coupling occurred, without affecting mechanical properties (Oki et al, 2019 ). On days following RGD coupling, fibroblasts proliferation significantly increased when compared to cells encapsulated within microcapsules where RGD was non-covalently bound or not present (Oki et al, 2019 ). Similarly, only when BMP-2 mimetic peptides were covalently bound to the alginate, preosteoblastic cells were able to differentiate into osteoblasts (Oki et al, 2019 ).…”

Establishment of Collagen: Hydroxyapatite/BMP-2 Mimetic Peptide Composites

“…BMP-2 mimetic peptides seem to trigger osteogenic differentiation of human bone marrow MSCs, as shown after simple functionalization of glass slides [22]. In a recent study, Oki and co-workers succeeded in the development of thiol-maleimide clickable alginate microcapsules containing biomimetic RGD and BMP-2 peptides [23]. Encapsulated mouse pre-osteoblastic cells started osteogenic differentiation when BMP-2 mimetic peptides were conjugated to microcapsules without the addition of further osteogenic agents.…”