Electrically Conductive Scaffold to Modulate and Deliver Stem Cells

Summary

This protocol describes fabrication of a cell culture system to allow seeding of stem cells on a conductive polymer scaffold for in vitro electrical stimulation and subsequent in vivo implantation of the stem cell-seeded scaffold using a minimally invasive technique.

Abstract

Stem cell therapy has emerged as an exciting stroke therapeutic, but the optimal delivery method remains unclear. While the technique of microinjection has been used for decades to deliver stem cells in stroke models, this technique is limited by the lack of ability to manipulate the stem cells prior to injection. This paper details a method of using an electrically conductive polymer scaffold for stem cell delivery. Electrical stimulation of stem cells using a conductive polymer scaffold alters the stem cell's genes involved in cell survival, inflammatory response, and synaptic remodeling. After electrical preconditioning, the stem cells on the scaffold are transplanted intracranially in a distal middle cerebral artery occlusion rat model. This protocol describes a powerful technique to manipulate stem cells via a conductive polymer scaffold and creates a new tool to further develop stem cell-based therapy.

Introduction

Stroke is the second leading cause of death in the world and the fifth leading cause of death in the United States. Despite these high death rates, treatments for stroke recovery currently remain a challenge with no viable medical options currently available¹. There are currently about 300 clinical trials dealing with ischemic strokes, of which only 40 utilize stem cells. Previous studies have shown that stem cell therapies have a beneficial effect on stroke repair^2,3. Paracrine factors such as brain-derived neurotrophic factor (BDNF) and thrombospondin-1 (THBS-1) released from transpla....

Protocol

All stem cell and animal procedures were approved by Stanford's Stem Cell Research Oversight committee and by Stanford University's Administrative Panel on Laboratory Animal Care (SCRO-616 and APLAC-31909).

1. Etching of ITO Glass

1. Prepare the indium tin oxide (ITO)-covered glass slide by placing a masking agent over the conductive side of the glass.
   NOTE: Most commercial transparent tapes can be used as a masking agent.
   1. Remove the excess mask using a blade, leaving only the desired shape of the final ITO design covered on the glass.
2. Combine 5% (v/v) of nitric acid and 45% (v/v) ....

Results

The schematic shown in Figure 1 represents the overall workflow of the electrical stimulation of hNPCs and potential downstream applications. A current limitation in stem cell therapy is that stem cells are exposed to a harsh post-transplantation environment including inflammation and ischemic conditions. These difficult conditions likely limit their therapeutic efficacy^14,15. The use of a conductive .......

Discussion

Growing evidence has demonstrated the promise of stem cells as a novel stroke therapy. This promise has resulted in a major effort to advance stem cell therapeutics to the bedside with at least 40 ongoing or completed clinical trials. Stroke pathology offers a unique neurological disorder that lends itself to stem cell therapy because after the acute insult, there is no neurodegenerative process preventing recovery. The exact mechanism of stem cell-enhanced stroke recovery remains unclear. Angiogenesis, synaptogenesis, a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
FGF-Basic	Invitrogen	CTP0261	20 ng/mL for working media
Matrigel	Corning	cb40234a	1:200 dilution
LIF Protein, Recom. Hum. (10 µg/mL)	EMD Millipore	LIF1010	10 ng/mL for working media
Sylgard 184 silicone 3.9 kg	Fisherbrand	NC0162601
Hydrochloric acid	Fisherbrand	SA56-4
Nitric Acid Concentrate (Certified) ACS, Fisher Chemical	Fisherbrand	SA95
ITO Glass	Delta Technologies	CG-40IN-0115
Sodium dodecylbenzenesulfonate	Sigma	289957-1KG
Pyrrole	Sigma	131709-500ML	Protect pyrrole solution from light and room temperature
8 well glass slide chambers	Thermo Sci Nuc	125658	Detach the cell chamber and keep it under sterilized conditions
Flat-Surface Bracket, 3"x1"	McMaster-Carr	1030A4
TWO PART SILVER PAINT 14G	Electron Microscopy Sciences	1264214	Mix two parts (1:1) in plastic plate
DPBS, 1x, with Ca and Mg, No Phenol Red	Genesse	25-508C
AB2 ArunA Neural Cell Culture Media Kit	Aruna Biomedical	ABNS7013.2
hNP1 Human Neural Progenitor Expansion Kit	Aruna Biomedical	hNP7013.1
Noncontact Flow-Adjustment Valve, Nickel-Plated Brass, for 3/32" to 5/8" Tube OD	McMaster-Carr	5330K22
Multimeter	Keysight	E3641A
Wavefoam generator	Keysight	33210A-10MHz
Pt meshes	Sigma-Aldrich	298107-425MG	Reference electrode with dimensions, 1x1 cm
LIVE/DEAD Viability/Cytotoxicity Kit, for mammalian cells	Thermo Fisher Scientific	L3224
BDNF	Thermo Fisher Scientific	Hs02718934_s1
THBS1	Thermo Fisher Scientific	Hs00962908_m1
GAPDH	Thermo Fisher Scientific	Hs02758991_g1
RNeasy Mini Kit (250)	Qiagen	74106
QIAshredder (250)	Qiagen	79656
RNase-Free DNase Set (50)	QIAGEN	79254
iScript cDNA Synthesis Kit, 100 x 20 µL rxns	BIORAD	1708891
TaqMan Gene Expression Master Mix	Thermo Fisher Scientific	4369510
7-8 Week Old, male, RNU Rats	NCI-Frederick
4-0 Ethicon Silk Suture	eSutures.com	683G
Isoflurane	Henry Schein	29405
V-1 Tabletop Laboratory Animal Anesthesia System	VetEquip	901806
Surgicel Original Absorbable Hemostat	Ethicon	1952
Lab Standard Stereotaxic Instrument, Rat	Stoelting	51600
Kimberly-Clark Professional Safeskin Purple Nitrile Sterile Exam Gloves	Fisherbrand	19-063-130
Sterile Drape	Medline	DYNJSD1092
Thermo Scientific Shandon Stainless-Steel Scalpel Blade Handle, Holds No. 20-25 Blades	Fisherbrand	53-34
Walter Stern Scalpel Blade Series 300	Fisherbrand	17-654-456
QuantStudio 6 Flex Real-Time PCR System	Thermo Fisher Scientific	4484642
Frazier Micro Dissecting Hook	Harvard Apparatus	52-2706