Christopher M Walthers

• University of California, Los Angeles

Introduction Biomaterials can provide localized reservoirs for controlled release of therapeutic biomolecules and drugs for applications in tissue engineering and regenerative medicine. As carriers of gene-based therapies, biomaterial scaffolds can improve efficiency and delivery-site localization of transgene expression. Controlled delivery of gen...

Neural stem/progenitor cell (NS/PC)‐based therapies have shown exciting potential for regeneration of the central nervous system (CNS) and NS/PC cultures represent an important resource for disease modeling and drug screening. However, significant challenges limiting clinical translation remain, such as generating large numbers of cells required fo...

Although critical for studies of gut motility and intestinal regeneration, the in vitro culture of intestinal muscularis with peristaltic function remains a significant challenge. Periodic contractions of intestinal muscularis result from the coordinated activity of smooth muscle cells (SMC), the enteric nervous system (ENS), and interstitial cells...

Contractions of cell clusters were represented by the intensity change. (A) Averaged fluorescence intensity of regions within the white boxes increased when the cell clusters contracted and decreased when the cell clusters relaxed. (B) For non-GFP cells in phase contrast videos, the mean intensity decreased (darker) as the cell cluster turned into...

Contractions of IMC at early time points in the muscularis medium. Distributions of contraction periods of IMC in the muscularis medium at day 7 (59, 6; N = 59 cell clusters from n = 6 biologically independent samples) and 14 (174, 7). (PDF)

Antibodies, primers and probes used in the study. (PDF)

Selected results of medium component assessment for IMC culture. (PDF)

Contractions of murine muscle strips (real time). Spontaneous periodic contractions of the non-GFP muscle strip (from a 5-day-old mouse) after 6-hour incubation in DMEM with ABAM at 37°C, corresponding to Fig 1C. Real time. Arrow indicates the spot tested to show the recording of intensity change in Fig 1C. N = 62 spots from n = 21 animals, and her...

No contractions in traditional serum medium (real time). Murine GFP IMC in the serum medium at day 7, 14, 21, 28, 35, 42, 49 and 56. No contractions were generated. Each about 30 seconds. All real time. All videos at different time points were taken from the same sample and this sample was from the same animals as the sample in S3 Video. n = 3 biol...

Carbachol effect, short and full versions (real time). Effects of carbachol on non-GFP murine IMC in the muscularis medium at day 28 (first a short version for a quick view of the effect, 00:00–00:47, then the full version, 00:47–04:05). Short version: First half (magnification, 40x): before adding carbachol (00:04–00:13), adding carbachol (00:13–0...

Niflumic acid effect (real time). Effects of 300 μM niflumic acid on non-GFP murine IMC in the muscularis medium at day 35. The video captures the same spot before (00:00–00:44) and after (00:44–01:29) adding 300 μM niflumic acid in culture. Arrow indicates the cell cluster tested to show the recording of intensity change in Fig 4C. Both real time....

TTX effect, muscle strips (speed 2x). Effects of TTX on non-GFP murine muscle strips (after 6-hour incubation in DMEM with ABAM at 37°C). First 1/3: before (00:01–00:23) and after (00:23–00:45) adding 10 μM TTX. 1/3 to 2/3: before (00:46–01:09) and after (01:09–01:31) adding 400 μM TTX. 2/3 to end: before (01:33–01:55) and after (01:55–02:17) addin...

Effects of DMPP, DMPP with Hexamethonium and DMPP with L-NAME (speed 2x). Effects of 10 μM DMPP, 10 μM DMPP with 300 μM hexamethonium or 10 μM DMPP with 100 μM L-NAME on non-GFP murine IMC in the muscularis medium at day 28. DMPP, 00:00–00:34: Before (00:00–00:17) and after (00:17–00:35) adding 10 μM DMPP in culture. Arrow indicates the cell cluste...

Epithelium moving with IMC in co-culture (real time). The movement of murine intestinal epithelium and IMC in the muscularis medium after co-cultured for 4 days. The arrow and asterisk indicate two epithelial clusters. The arrow points to the epithelial cell cluster tested to show the deformation in Fig 7G and 7H. Real time. n = 6 biologically inde...

IMC in the EC medium displayed neurites-like structure. Representative GFP fluorescence image of murine IMC in EC medium at day 7. The arrow indicates the neurites-like fibers in culture. Scale bar, 200 μm. (PDF)

The presence of Nac substantially limited the survival of mature human smooth muscle cells. MHC (smooth muscle cells) and β-Tub III (neurons) staining of human fetal IMC in muscularis medium (with Nac) and human muscularis medium (without Nac) after 21-day culture. DAPI (blue) stained the nuclei. Scale bars, 500 μm. (PDF)

Representative murine IMC contractions (real time). Two samples of spontaneously and periodically contracting murine IMC in the muscularis medium. They are biologically independent. Sample 1 is GFP IMC in the muscularis medium at day 19 (00:00 to 00:30, 30 seconds); Sample 2 is non-GFP IMC in the muscularis medium at day 28 (00:30 to 01:33, ~1 minu...

IMC contractions d7-d56 (real time). Spontaneous and periodic contractions of GFP murine IMC in the muscularis medium at day 7, 14, 21, 28, 35, 42, 49 and 56, corresponding to Fig 1B and 1C and S4 Fig. Each about 30 seconds. All real time. All videos at different time points were taken from the same sample. n = 4 biologically independent samples, a...

Contractions of filtered IMC (real time). Spontaneous and periodic contractions of filtered murine IMC in the muscularis medium for 21 days. Real time. n = 3 biologically independent samples, and here only one representative sample is shown. Magnification, 40x. Contractile assessments were conducted at room temperature (22 to 25°C). (MP4)

Calcium propagation (real time). Ca2+ flux propagation in murine IMC cultured in the muscularis medium for 28 days, corresponding to Fig 4E. Real time. n = 3 biologically independent samples, and here only one representative sample is shown. Magnification, 100x. Contractile assessments were conducted at room temperature (22 to 25°C). (MP4)

TTX effect (speed 2x). Effects of TTX on non-GFP murine IMC in the muscularis medium at day 28. First half: before (00:00–00:23) and after (00:23–00:45) adding 10 μM TTX in culture. Second half: before (00:46–01:09) and after (01:09–01:31) adding 400 μM TTX in culture. Arrows indicate the cell clusters tested to show the recording of intensity chan...

IMC on scaffold (real time). Spontaneously and periodically contracting murine IMC sheets on PCL scaffolds in the muscularis medium at day 21(00:00–00:30) and day 28 (00:30–01:00), matching the recording of intensity change in Fig 6A. Both real time. n = 3 biologically independent samples, and here only one representative sample is shown. Magnifica...

Contractions of human IMC (speed 20x). Spontaneous (no stimulation) and periodic contractions of human IMC in the human muscularis medium. First half: 16-week-old human fetal IMC in the human muscularis medium. (Sample 1 at day 14: 00:03–00:17; Sample 1 at day 28: 00:17–00:32; Sample 2 at day 14: 00:32–00:47). Sample 1 is the same muscularis comple...

Human epithelium moving with IMC (speed 20x). The movement of human intestinal epithelium and IMC in the human muscularis medium after co-cultured for 4 days. The arrow points to one epithelial cell cluster sitting on top of the contracting IMC. n = 3 biologically independent samples. Magnification, 100x. This video is at 20x speed. Contractile ass...

BSA (real time). Spontaneous (no stimulation) and periodic contractions of non-GFP murine IMC in the muscularis medium at day 28, initial pre-incubation without serum, corresponding to S2 Note. Real time. n = 3 biologically independent samples, and here only one representative sample is shown. Magnification, 100x. Contractile assessments were condu...

Contraction frequency test for GFP cells (strong background noise). (PDF)

Contraction frequency test for non-GFP cells. (PDF)

Effects of TTX on fresh muscle strips and IMC in the muscularis medium. (A) Representative recordings of the effect of TTX at 400 μM on IMC in the muscularis medium at d28, matching S14 Video. (B) Representative recordings of the effects of TTX at 10 μM, 400 μM and 1 mM on fresh muscle strips, matching S15 Video. (PDF)

Serosal mesothelial cells also existed in epithelium-muscularis co-culture. Immunofluorescence of cytokeratin after 4-day co-culture of epithelium and IMC. Scale bar, 200 μm. (PDF)

Periodic contractions of human postnatal IMC in the human muscularis medium. (A) Recordings of periodic contractions of one human infant IMC cluster in the human muscularis medium at day 22 (S19 Video). (B) Recordings of periodic contractions of one human postnatal IMC cluster in the human muscularis medium at day 28 (left) and its phase contrast i...

Rendering the culture condition totally serum-free. (PDF)

Calcium oscillations (real time). Spontaneous periodic Ca2+ oscillations of murine IMC in the muscularis medium for 28 days. Arrow indicates the cell cluster tested to show the recording of intensity change in Fig 4D. Real time. n = 3 biologically independent samples, and here only one representative sample is shown. Magnification, 100x. Contractil...

Drug vehicles (distilled water and DMSO) had little effect on the contraction frequency of IMC in the muscularis medium. (A) Representative recordings of the immediate effect of distilled water on IMC in the muscularis medium at d28 (n = 3 biologically independent samples). (B) Representative recordings of the effect of distilled water on IMC in th...

The expression of c-Kit decreased when noggin, R-spondin1 and Y27632 (NRY) were removed from the muscularis medium. (A) Immunofluorescence of c-Kit at day 7 and 28 (n = 3 biologically independent samples). Scale bars, 200 μm. (B) Relative mRNA expression of c-Kit in the serum medium, muscularis medium and the medium without NRY at day 2 (pre-incuba...

Components in the EC medium and their possible functions in IMC culture. (PDF)

The development of the muscularis medium for IMC culture. (PDF)

Contractions of passaged IMC (real time). Contractions of murine IMC initially cultured in the serum medium for 4 days then passaged and cultured for 14 days. Passaged cells were cultured in the muscularis medium. Real time. n = 3 biologically independent samples, and here only one representative sample is shown. Magnification, 40x. Contractile ass...

Carbachol effect, muscle strips (real time). Effects of carbachol on murine muscle strips (after 6-hour incubation in DMEM with ABAM at 37°C). First half: before adding carbachol (00:02–00:39), adding carbachol (00:39–00:50) and after adding 50 μM carbachol (00:50–01:45); second half: before adding carbachol (01:47–02:15), adding carbachol (02:15–0...

SNP effect (real time). Effects of 100 μM SNP on non-GFP murine IMC in the muscularis medium at day 28. The video captures the same spot before (00:00–01:00) and after (01:00–02:00) adding 100 μM SNP in culture. Arrow indicates the cell cluster tested to show the recording of intensity change in Fig 4A. Both real time. n = 3 biologically independen...

Niflumic acid effect, muscle strips (real time). Effects of 300 μM niflumic acid on non-GFP murine muscle strips (after 6-hour incubation in DMEM with ABAM at 37°C). The video captures the same muscle strip before (00:00–00:45) and after (00:45–01:30) adding 300 μM niflumic acid. Both real time. n = 6 animals, and here only one representative sampl...

Human muscle strips (speed 20x). Spontaneous and periodic contractions of the human fetal muscle strip (16-week-old) after 2-day incubation in DMEM with ABAM at 37°C. n = 3 biologically independent samples, and here only one representative spot is shown. Magnification, 40x. This video is at 20x speed. Contractile assessments were conducted at room...

Contraction frequency test for GFP cells. (PDF)

Glioblastoma (GBM) tumors exhibit potentially actionable genetic alterations against which targeted therapies have been effective in treatment of other cancers. However, these therapies have largely failed in GBM patients. A notable example is kinase inhibitors of EGFR, which display poor clinical efficacy despite overexpression and/or mutation of...

Although critical for studies of gut motility and intestinal regeneration, the in vitro culture of intestinal muscularis with peristaltic function remains a significant challenge. Periodic contractions of intestinal muscularis result from the coordinated activity of smooth muscle cells (SMC), the enteric nervous system (ENS), and interstitial cells...

The spinal cord is unable to regenerate after injury largely due to growth-inhibition by an inflammatory response to the injury that fails to resolve, resulting in secondary damage and cell death. An approach that prevents inhibition by attenuating the inflammatory response and promoting its resolution through the transition of macrophages to anti-...

Tissue engineering is an innovative field of research applied to treat intestinal diseases. Engineered smooth muscle requires dense smooth muscle tissue and robust vascularization to support contraction. The purpose of this study was to use heparan sulfate (HS) and collagen coatings to increase the attachment of smooth muscle cells (SMCs) to scaffo...

Gene therapies hold great promise for the treatment of many neurodegenerative disorders and traumatic injuries in the central nervous system. However, development of effective methods to deliver such therapies in a controlled manner to the spinal cord is a necessity for their translation to the clinic. Although essential progress has been made to i...

Functionally contracting smooth muscle is an essential part of the engineered intestine that has not been replicated in vitro. The purpose of this study is to produce contracting smooth muscle in culture by maintaining the native smooth muscle organization. We employed intact smooth muscle strips and compared them to dissociated smooth muscle cells...

Purpose Distraction enterogenesis is a potential treatment for patients with short bowel syndrome. We previously demonstrated successful lengthening of jejunum using a degradable spring device in rats. Absorptive function of the lengthened jejunum after restoration into intestinal continuity needs to be determined. Methods Encapsulated polycaprola...

To investigate the efficacy of biomimetic PLGA scaffolds, alone and in combination with bone morphogenic protein (BMP-2) and adipose-derived stem cells (ASCs), to heal a critical-sized segmental mandibular defect in a rat model. Study Design Prospective animal study. Methods ASCs were isolated and cultured from the inguinal fat of Lewis rat pups....

Angiogenesis and survival of cells within thick scaffolds is a major concern in tissue engineering. The purpose of this study is to increase the survival of intestinal smooth muscle cells (SMCs) in implanted tissue-engineered constructs. We incorporated 250-μm pores in multi-layered, electrospun scaffolds with a macroporosity ranging from 15% to 25...

Purpose Distraction enterogenesis, a method of using mechanical force to lengthen existing intestine, has recently evolved as a potential treatment for short bowel syndrome. We previously demonstrated successful lengthening of rat jejunum using a degradable spring device. Although lengthened jejunal segments have been successfully restored into i...

Background: One of the greatest challenges in scaffold-based tissue engineering remains poor and inefficient penetration of cells into scaffolds to generate thick vascularized and cellular tissues. Electrospinning has emerged as a preferred method for producing scaffolds with high surface area-to-volume ratios and resemblance to extracellular matr...

Passive and label-free isolation of viable target cells based on intrinsic biophysical cellular properties would allow for cost savings in applications where molecular biomarkers are known as well as potentially enable the separation of cells with little-to-no known molecular biomarkers. We have demonstrated the purification of adrenal cortical pro...

Macroporous polymeric microparticles have been fabricated using a combination of particulate leaching and gas foaming techniques. Controlling the concentration of ammonium bicarbonate particles and the spin speed of the microemulsion in poly (ε-caprolactone) (PCL) yields a range of macroporous microparticles with interconnected pores (10-50µm) that...