product photo of CTS KnockOut SR XenoFree Medium bottle

Gibco CTS KnockOut SR XenoFree Medium is a xeno-free culture supplement that maintains pluripotency, normal morphology, and karyotype of human pluripotent stem cells (PSCs). It exhibits performance equivalent to that of traditional Gibco KnockOut Serum Replacement and supports the derivation and routine maintenance of human ESCs and iPSCs.

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CTS KnockOut SR XenoFree features

  • Defined, xeno-free composition—formulated exclusively with human-derived or human-recombinant proteins, eliminating non-human animal components.
  • Supports long-term maintenance of stem cells—human embryonic stem cells (hESCs) and human induced PSCs have preserved pluripotency, normal morphology, and stable karyotype.
  • Validated for clinical-translation workflows—enables feeder-dependent PSC culture using human feeder cells and CELLstart substrate, and supports derivation, cryopreservation, and differentiation applications.
  • Facilitates regulatory insights and streamlined manufacturing—part of the CTS product line, which includes documentation (Certificates of Analysis, Certificates of Origin), and designed to reduce reagent-qualification during clinical development.
  • Serum-free, xeno-free classification and manufactured under quality standards (ISO 13485, MDSAP, 21 CFR 820)—suitable for cell therapy research, development, and manufacturing.
  • Versatile for multiple applications in stem-cell workflows—including PSC expansion/maintenance, derivation of new lines, differentiation studies and cryopreservation of hESCs/PSCs.


Performance data of hESCs cultured in CTS KnockOut SR XenoFree Medium

CTS KnockOut SR XenoFree Medium supports the growth and pluripotency of hESCs and PSCs under xeno-free conditions.

phase contrast microscopy images of BG01v cells showing expression of DAPI, Oct4, and SSEA4

Figure 1. hESCs cultured in KnockOut SR XenoFree Medium retain their pluripotent phenotype. BG01v cells cultured using CTS KnockOut SR XenoFree Medium maintain expression of common hESC markers. BG01v cells were cultured on human foreskin fibroblasts and CELLstart Substrate for 5 passages prior to immunocytochemical staining. (A) Phase contrast; (B) DAPI; (C) Oct4; (D) SSEA4 Alexa Fluor 488 and 555, respectively.

panel a is a phase contrast microscopy image of hESCs in CTS KnockOut SR XenoFree Medium and panel b shows expression of common pluripotency markers
Figure 2. Xeno-free culture and gene expression of hESCs. (A) Xeno-free culture of hESCs on feeder cells. BG01v morphology when cultured using CTS KnockOut SR XenoFree Medium on human foreskin fibroblasts (HFF) attached with CELLstart Substrate, passage 4. (B) Maintenance of pluripotency with CTS KnockOut SR XenoFree Medium. Following 10 passages in either medium supplemented with KnockOut Serum replacement (left lane of the pair for each marker) or CTS KnockOut SR XenoFree medium (right lane of the pair for each marker) on HFF attached with CELLstart Substrate, BG01v gene expression was examined (top). Gene expression of embryoid bodies generated from the same passage-10 BG01v/HFF culture (bottom).


Recommended media system

SupplementBasal mediumRecommended reagent
CTS KnockOut SR XenoFree MediumCTS KnockOut DMEMCTS CELLstart substrate

CTS KnockOut SR XenoFree Medium resources

Related pages

For Research Use or Manufacturing of Cell, Gene, or Tissue-Based Products. CAUTION: Not intended for direct administration into humans or animals.

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