Neural induction – Dual SMAD inhibition |
Prepared by: |
Date Submitted |
April 5, 2012 |
Submitted by |
Mark Tomishima tomishim@mskcc.org |
Adapted from |
Chambers et al., 2009 |
Contributor |
Mark Tomishima |
Affiliation |
Sloan-Kettering Institute |
Dual SMAD inhibition takes a confluent, feeder free culture of hPSCs and rapidly differentiates them into early neurectoderm. This rapid differentiation is caused by blocking the two signaling pathways that utilize SMADs for transduction: BMP and TGFB. Oct4 is extinguished and Pax6 expression has begun by around day 7-8, depending on the line used. This neurectoderm can be passaged to become rosettes or can be patterning to become many other types of neural cells (for example, see Fasano et al., 2010).
Neural induction
Mechanical dissociation (variation 1)
Single cell passage (variation 2)
Neuronal differentiation
Reagents | Supplier | Catalog # | Notes |
---|---|---|---|
45 µM nylon mesh cell strainers | BD Falcon | 352340 | |
1xDPBS | Life Technologies | 14190 | |
0.1% gelatin in PBS | Chemicon/Millipore | ES-0060B | |
Dispase | StemCell Technologies | 07913 | Store it at -20°C in working aliquots |
FGF2 | R&D Systems | 233-FB-001MG/CF | Dissolve in PBS with 0.1% BSA to 100 ug/ml stock |
Noggin/Fc Chimera | R&D Systems | 719-NG | Dissolve in PBS with 0.1% BSA to 100 ug/ml |
BDNF | R&D Systems | 248-BD | Dissolve in PBS with 0.1% BSA to 100 ug/ml |
SHH (C25II)* | R&D Systems | 464-SH | Dissolve in PBS with 0.1% BSA to 100 ug/ml |
Fgf8 | R&D Systems | 423-F8 | Dissolve in PBS with 0.1% BSA to 100 ug/ml |
GDNF | Peprotech | 450-10 | Dissolve in PBS with 0.1% BSA to 10 ug/ml |
TGF-B3 | R&D Systems | 243-B3 | Dissolve in 4mM HCl containing 0.1% BSA to 20 ug/ml |
Dll4 | R&D Systems | 1506-D4-050 | Dissolved in 1x DPBS containing 0.1% BSA to 200 µg/ml |
dbcAMP | Sigma | D0260 | Dissolved in sterile water to 100 mM |
Retinoic acid | Sigma | R2625 | Dissolve in DMSO to 10 mM. Protect from light and freeze/thaw only 3 times |
Ascorbic acid | Sigma | A5960 | Add 1.76g/100 ml sterile water and filter sterilize. |
SB431542 | Tocris Bioscience | 1614 | Dissolve in 100% ethanol to 10 mM. |
LDN189193 | |||
Y-27632 | Tocris Bioscience | 1254 | Dissolve in sterile filtered water to 10 mM |
Matrigel** | BD Bioscience | 352340 | We only use lots of Matrigel over 10 mg/ml protein |
MEFs | GlobalStem, Inc. | GSC-6001M |
*SHH can be purchased that is either mouse or human (although they are 92% identical at the amino acid level). Furthermore, it can be purchased with engineered isoleucines on the N- terminus: these modifications make the protein more hydrophobic and likely act as a membrane tether and intercellular transport mechanism. The engineered modifications phenocopy the cholesterol and palmitate modifications that occur in mammalian cells and are necessary since bacterial expression of the protein does not provide these mammalian modifications. Most of our previous work uses conventional SHH (such as R&D Systems cat. # 461-SH) but we have found that it is more economical to use 10-fold less of the isoleucine-modified version./p>
**Matrigel Basement Membrane Matrix (BD Bioscience; cat. no. 354234: we only use lots that contain over 10 mg/ml protein). Thaw the frozen vial of Matrigel on ice overnight in a 4°C refrigerator. Prepare 1 mL aliquots in a 50 mL centrifuge tube using chilled pipettes and freeze at -20°C. Matrigel must be thawed slowly to prevent gelatinization. Chilled pipettes and 50 mL centrifuge tubes should be used when making aliquots of the Matrigel./p>
MEF media
900 ml DMEM (Invitrogen cat.# 11965-118) 100 ml FBS (Invitrogen, cat.# 26140-095)
Filter sterilize./p>
hPSC media
790 ml DMEM:F12 (Invitrogen, cat.# 11330-032)
200 ml Knockout serum replacement (SRM; Invitrogen, cat. no. 10828-028)
5 ml L-glutamine (200 mM, Invitrogen, cat.# 25030-081)
10 mL MEM non-essential amino acids (MEM NEAA; Invitrogen, cat.# 11140-050)
1 mL of 2-mercaptoethanol (Invitrogen, cat.# 21985-023)
The medium is sterile filtered in the hood and FGF2 is added after filtration to a final concentration of 6 ng/ml./p>
SRM media
820 mL of Knockout DMEM (Invitrogen; cat. no. 10829-018), 150 mL Knockout Serum Replacement (Invitrogen, cat. no. 10828-028), 10 mL L-glutamine (200 mM, Invitrogen, cat. no. 25030-081), 10 mL MEM NEAA (Invitrogen, cat. no. 11140-050), and 1 mL of 2-mercaptoethanol (Invitrogen, cat. no. 21985-023)./p>
MEF conditioned media (CM)
MEF CM is harvested from MEF coated flasks. MEFs are plated at a density of 50,000 cells/cm2 in a T225 flask in MEF media. The next day, the cells are washed once with PBS before adding 100 mL of hESC media. Incubate media with MEFs for 24 hours before removal. The medium is now known as “conditioned media” (CM) and can be directly used or stored at 4°C for less than two weeks. Additional hESC media can be conditioned daily for up to ten days on the same flask of feeders. Just before using, FGF2 is added to CM to a final concentration of 10 ng/mL, hereafter called complete CM (cCM)./p>
N2 media
N2 media contains DMEM/ F12 powder (Gibco/Invitrogen, cat no. 12500-062) in 550 mL of distilled water. 1.55 g of glucose (Sigma, cat. no. G7021), 2.00 g of sodium bicarbonate (Sigma, cat. no. S5761), putrescine (1 ml aliquot of 1.61 g dissolved in 100 mL of distilled water; Sigma, cat. no. P5780), progesterone (20 uL aliquot of 0.032g dissolved in 100 mL 100% ethanol; Sigma, cat. no. P8783), sodium selenite (60 uL aliquot of 0.5 mM solution in distilled water; Bioshop Canada, cat. no. SEL888), and 100 mg of transferrin (Celliance/Millipore, cat. no. 4452-01) are added. 25 mg of powdered insulin (Sigma, cat. no. I6634) is added to 10 mL of 5 mM NaOH and is shaken until completely dissolved. The solubilized insulin is added to the media, and double-distilled water (with a resistance of 18.2 MΩ) is added to a final volume of 1000 mL before sterile filtration.
***Recently, the Studer and Tomishima labs have had problems with the supply chain for this media. This has caused us to explore new sources, and many are now using Neurobasal with N2 supplements and B27 (without retinoic acid) and L-glutamine.
Q: I am having problems passaging at day 10 – what’s wrong?
A: You have to keep a very high cell density for passage. Low densities do not survive well and will not rosette, particularly for the single cell passage. It might help to use Y-27632 to promote survival.
Q: I have seen many different cell densities for the start of neural induction. What’s the right number?
A: Basically, you need to have confluent PSCs. We used to passage as singles and expand them in place before differentiation, but most of us now plate at saturating densities (200,000 cells/cm2), allow the cells to recover overnight, then induce differentiation. It might also be possible to induce differentiation at the replating point but I have not tried this yet.
Q: N2 is hard. Is there an easier way?
A: Maybe. Most people around here have switched to NeuroBasal with B27 (no RA) and N2 supplements (Stem Cell Technologies), L-glut and glucose as an alternative. This has seemingly fixed our inconsistencies with some differentiation protocols, but your mileage might vary. We do not yet have a clear understanding of what this could do to downstream differentiations.
This page was last modified on October 23, 2012